Repository: yt-dlp/yt-dlp

Issue:
MagellanTV not downloading
### Checklist

- [x] I'm reporting that yt-dlp is broken on a **supported** site
- [x] I've verified that I have **updated yt-dlp to nightly or master** ([update instructions](https://github.com/yt-dlp/yt-dlp#update-channels))
- [x] I've checked that all provided URLs are playable in a browser with the same IP and same login details
- [x] I've checked that all URLs and arguments with special characters are [properly quoted or escaped](https://github.com/yt-dlp/yt-dlp/wiki/FAQ#video-url-contains-an-ampersand--and-im-getting-some-strange-output-1-2839-or-v-is-not-recognized-as-an-internal-or-external-command)
- [x] I've searched [known issues](https://github.com/yt-dlp/yt-dlp/issues/3766), [the FAQ](https://github.com/yt-dlp/yt-dlp/wiki/FAQ), and the [bugtracker](https://github.com/yt-dlp/yt-dlp/issues?q=is%3Aissue%20-label%3Aspam%20%20) for similar issues **including closed ones**. DO NOT post duplicates
- [x] I've read about [sharing account credentials](https://github.com/yt-dlp/yt-dlp/blob/master/CONTRIBUTING.md#are-you-willing-to-share-account-details-if-needed) and I'm willing to share it if required

### Region

Europe

### Provide a description that is worded well enough to be understood

I believe it has something to do with the videos coming from cloudfront cdn.



### Provide verbose output that clearly demonstrates the problem

- [x] Run **your** yt-dlp command with **-vU** flag added (`yt-dlp -vU <your command line>`)
- [ ] If using API, add `'verbose': True` to `YoutubeDL` params instead
- [x] Copy the WHOLE output (starting with `[debug] Command-line config`) and insert it below

### Complete Verbose Output

```shell
❯ yt-dlp -vU "https://www.magellantv.com/watch/animal-doctors?type=v"
[debug] Command-line config: ['-vU', 'https://www.magellantv.com/watch/animal-doctors?type=v']
[debug] Encodings: locale utf-8, fs utf-8, pref utf-8, out utf-8, error utf-8, screen utf-8
[debug] yt-dlp version stable@2025.02.19 from yt-dlp/yt-dlp [4985a4041]
[debug] Python 3.13.2 (CPython x86_64 64bit) - Linux-6.13.4-zen1-1-zen-x86_64-with-glibc2.41 (OpenSSL 3.4.1 11 Feb 2025, glibc 2.41)
[debug] exe versions: ffmpeg 7.1 (setts), ffprobe 7.1
[debug] Optional libraries: Cryptodome-3.21.0, brotlicffi-1.1.0.0, certifi-2025.01.31, pyxattr-0.8.1, requests-2.32.3, sqlite3-3.49.1, urllib3-2.3.0, websockets-12.0
[debug] Proxy map: {}
[debug] Request Handlers: urllib, requests
[debug] Loaded 1841 extractors
[debug] Fetching release info: https://api.github.com/repos/yt-dlp/yt-dlp/releases/latest
Latest version: stable@2025.02.19 from yt-dlp/yt-dlp
yt-dlp is up to date (stable@2025.02.19 from yt-dlp/yt-dlp)
[MagellanTV] Extracting URL: https://www.magellantv.com/watch/animal-doctors?type=v
[MagellanTV] animal-doctors: Downloading webpage
ERROR: animal-doctors: An extractor error has occurred. (caused by KeyError('jwpVideoUrl')); please report this issue on  https://github.com/yt-dlp/yt-dlp/issues?q= , filling out the appropriate issue template. Confirm you are on the latest version using  yt-dlp -U
  File "/usr/lib/python3.13/site-packages/yt_dlp/extractor/common.py", line 746, in extract
    ie_result = self._real_extract(url)
  File "/usr/lib/python3.13/site-packages/yt_dlp/extractor/magellantv.py", line 49, in _real_extract
    formats, subtitles = self._extract_m3u8_formats_and_subtitles(data['jwpVideoUrl'], video_id)
                                                                  ~~~~^^^^^^^^^^^^^^^
KeyError: 'jwpVideoUrl'
```

Discussion:
@dirkf: Now, the site doesn't need an extractor for media: use `--ies=generic` (upstream: `--force-generic`).@Jogai: Thanks a lot. That works. (Without subs, just to be complete, but that doesn't bother me).@dirkf: Not so fast, though! For me the generic extraction is getting the next episode 'Super Moss'.

The target sought by the extractor has changed from camel to snake case: `jwp_video_url`. However the JSON in the problem page doesn't have this member, although the similar object for `next_episode` that is also included **does** have it. The extractor should use a traversal path like `(('manifests', ('v2', ...), 'hls'), 'jwp_video_url'), {url_or_none}, any`, where `v2` is pulled out because it seems to be the manifest version that has subtitles when there are any (otherwise `.jwp_captions` may have an object with `.file` being the URL and `.language`).

The Generic embed extraction finds, among a lot of other things, anything like `...video_url':'http...`. This accidentally catches the `jwp_video_url':...` in the `next_episode` JSON when the actual episode's `detail` doesn't have it.

Also, some of the search patterns in this old Generic code start with an apparently redundant `[^A-Za-z0-9]?` (meaning 'optionally match a non-alphanumeric character') -- I have no idea why.@Jogai: I wanted to get 2 different videos, and both worked fine. Should I reopen the issue for the problems you encountered?@dirkf: Could you please try the command below and check the resulting image file `adthumb.jpg` to see if it's the same as the one I got, as attached?
 
![adthumb](https://github.com/user-attachments/assets/1f354793-8588-49ee-835e-0d3e611ab54c)

It seems to be a frame of the show 'Super Moss' (the next episode linked in the page), rather than the episode 'Animal Doctors' as wanted (I only watched a minute or so of the video, but it was very mossy).

If the image is the same, the issue still needs work and should be re-opened. But a koala with a stethoscope or whatever would indicate that all's well and I need to work out why.

The command:
```shell
yt-dlp -f worstvideo -o - 'https://www.magellantv.com/watch/animal-doctors?type=v' --ies=generic | ffmpeg -ss 00:00:10.000 -hide_banner -v 0 -i - -vframes 1 -update 1 -y adthumb.jpg
```
The terminal output should look s/t like this:
```console
[generic] Extracting URL: https://www.magellantv.com/watch/animal-doctors?type=v
[generic] animal-doctors?type=v: Downloading webpage
WARNING: [generic] Falling back on generic information extractor
[generic] animal-doctors?type=v: Extracting information
[generic] stream: Downloading m3u8 information
[generic] stream: Checking m3u8 live status
[info] stream: Downloading 1 format(s): 370
[hlsnative] Downloading m3u8 manifest
WARNING: Live HLS streams are not supported by the native downloader. If this is a livestream, please add "--downloader ffmpeg --hls-use-mpegts" to your command
[hlsnative] Total fragments: 783
[download] Destination: -
[download]   0.4% of ~  89.07MiB at  120.47KiB/s ETA 09:47 (frag 4/783)ERROR: Unable to download video: [Errno 32] Broken pipe
```
@Jogai: Sorry, you were right. Both videos i downloaded were different than I expected.

Solution patch:
diff --git a/yt_dlp/extractor/magellantv.py b/yt_dlp/extractor/magellantv.py
index 6f2524ba2..e7ae709cf 100644
--- a/yt_dlp/extractor/magellantv.py
+++ b/yt_dlp/extractor/magellantv.py
@@ -1,35 +1,36 @@
 from .common import InfoExtractor
-from ..utils import parse_age_limit, parse_duration, traverse_obj
+from ..utils import parse_age_limit, parse_duration, url_or_none
+from ..utils.traversal import traverse_obj
 
 
 class MagellanTVIE(InfoExtractor):
     _VALID_URL = r'https?://(?:www\.)?magellantv\.com/(?:watch|video)/(?P<id>[\w-]+)'
     _TESTS = [{
-        'url': 'https://www.magellantv.com/watch/my-dads-on-death-row?type=v',
+        'url': 'https://www.magellantv.com/watch/incas-the-new-story?type=v',
         'info_dict': {
-            'id': 'my-dads-on-death-row',
+            'id': 'incas-the-new-story',
             'ext': 'mp4',
-            'title': 'My Dad\'s On Death Row',
-            'description': 'md5:33ba23b9f0651fc4537ed19b1d5b0d7a',
-            'duration': 3780.0,
+            'title': 'Incas: The New Story',
+            'description': 'md5:936c7f6d711c02dfb9db22a067b586fe',
             'age_limit': 14,
-            'tags': ['Justice', 'Reality', 'United States', 'True Crime'],
+            'duration': 3060.0,
+            'tags': ['Ancient History', 'Archaeology', 'Anthropology'],
         },
         'params': {'skip_download': 'm3u8'},
     }, {
-        'url': 'https://www.magellantv.com/video/james-bulger-the-new-revelations',
+        'url': 'https://www.magellantv.com/video/tortured-to-death-murdering-the-nanny',
         'info_dict': {
-            'id': 'james-bulger-the-new-revelations',
+            'id': 'tortured-to-death-murdering-the-nanny',
             'ext': 'mp4',
-            'title': 'James Bulger: The New Revelations',
-            'description': 'md5:7b97922038bad1d0fe8d0470d8a189f2',
+            'title': 'Tortured to Death: Murdering the Nanny',
+            'description': 'md5:d87033594fa218af2b1a8b49f52511e5',
+            'age_limit': 14,
             'duration': 2640.0,
-            'age_limit': 0,
-            'tags': ['Investigation', 'True Crime', 'Justice', 'Europe'],
+            'tags': ['True Crime', 'Murder'],
         },
         'params': {'skip_download': 'm3u8'},
     }, {
-        'url': 'https://www.magellantv.com/watch/celebration-nation',
+        'url': 'https://www.magellantv.com/watch/celebration-nation?type=s',
         'info_dict': {
             'id': 'celebration-nation',
             'ext': 'mp4',
@@ -43,10 +44,19 @@ class MagellanTVIE(InfoExtractor):
     def _real_extract(self, url):
         video_id = self._match_id(url)
         webpage = self._download_webpage(url, video_id)
-        data = traverse_obj(self._search_nextjs_data(webpage, video_id), (
-            'props', 'pageProps', 'reactContext',
-            (('video', 'detail'), ('series', 'currentEpisode')), {dict}), get_all=False)
-        formats, subtitles = self._extract_m3u8_formats_and_subtitles(data['jwpVideoUrl'], video_id)
+        context = self._search_nextjs_data(webpage, video_id)['props']['pageProps']['reactContext']
+        data = traverse_obj(context, ((('video', 'detail'), ('series', 'currentEpisode')), {dict}, any))
+
+        formats, subtitles = [], {}
+        for m3u8_url in set(traverse_obj(data, ((('manifests', ..., 'hls'), 'jwp_video_url'), {url_or_none}))):
+            fmts, subs = self._extract_m3u8_formats_and_subtitles(
+                m3u8_url, video_id, 'mp4', m3u8_id='hls', fatal=False)
+            formats.extend(fmts)
+            self._merge_subtitles(subs, target=subtitles)
+        if not formats and (error := traverse_obj(context, ('errorDetailPage', 'errorMessage', {str}))):
+            if 'available in your country' in error:
+                self.raise_geo_restricted(msg=error)
+            self.raise_no_formats(f'{self.IE_NAME} said: {error}', expected=True)
 
         return {
             'id': video_id,
diff --git a/yt_dlp/networking/_requests.py b/yt_dlp/networking/_requests.py
index 7de95ab3b..23775845d 100644
--- a/yt_dlp/networking/_requests.py
+++ b/yt_dlp/networking/_requests.py
@@ -296,6 +296,7 @@ def _check_extensions(self, extensions):
         extensions.pop('cookiejar', None)
         extensions.pop('timeout', None)
         extensions.pop('legacy_ssl', None)
+        extensions.pop('keep_header_casing', None)
 
     def _create_instance(self, cookiejar, legacy_ssl_support=None):
         session = RequestsSession()
@@ -312,11 +313,12 @@ def _create_instance(self, cookiejar, legacy_ssl_support=None):
         session.trust_env = False  # no need, we already load proxies from env
         return session
 
-    def _send(self, request):
-
-        headers = self._merge_headers(request.headers)
+    def _prepare_headers(self, _, headers):
         add_accept_encoding_header(headers, SUPPORTED_ENCODINGS)
 
+    def _send(self, request):
+
+        headers = self._get_headers(request)
         max_redirects_exceeded = False
 
         session = self._get_instance(
diff --git a/yt_dlp/networking/_urllib.py b/yt_dlp/networking/_urllib.py
index 510bb2a69..a188b35f5 100644
--- a/yt_dlp/networking/_urllib.py
+++ b/yt_dlp/networking/_urllib.py
@@ -379,13 +379,15 @@ def _create_instance(self, proxies, cookiejar, legacy_ssl_support=None):
         opener.addheaders = []
         return opener
 
-    def _send(self, request):
-        headers = self._merge_headers(request.headers)
+    def _prepare_headers(self, _, headers):
         add_accept_encoding_header(headers, SUPPORTED_ENCODINGS)
+
+    def _send(self, request):
+        headers = self._get_headers(request)
         urllib_req = urllib.request.Request(
             url=request.url,
             data=request.data,
-            headers=dict(headers),
+            headers=headers,
             method=request.method,
         )
 
diff --git a/yt_dlp/networking/_websockets.py b/yt_dlp/networking/_websockets.py
index ec55567da..7e5ab4600 100644
--- a/yt_dlp/networking/_websockets.py
+++ b/yt_dlp/networking/_websockets.py
@@ -116,6 +116,7 @@ def _check_extensions(self, extensions):
         extensions.pop('timeout', None)
         extensions.pop('cookiejar', None)
         extensions.pop('legacy_ssl', None)
+        extensions.pop('keep_header_casing', None)
 
     def close(self):
         # Remove the logging handler that contains a reference to our logger
@@ -123,15 +124,16 @@ def close(self):
         for name, handler in self.__logging_handlers.items():
             logging.getLogger(name).removeHandler(handler)
 
-    def _send(self, request):
-        timeout = self._calculate_timeout(request)
-        headers = self._merge_headers(request.headers)
+    def _prepare_headers(self, request, headers):
         if 'cookie' not in headers:
             cookiejar = self._get_cookiejar(request)
             cookie_header = cookiejar.get_cookie_header(request.url)
             if cookie_header:
                 headers['cookie'] = cookie_header
 
+    def _send(self, request):
+        timeout = self._calculate_timeout(request)
+        headers = self._get_headers(request)
         wsuri = parse_uri(request.url)
         create_conn_kwargs = {
             'source_address': (self.source_address, 0) if self.source_address else None,
diff --git a/yt_dlp/networking/common.py b/yt_dlp/networking/common.py
index e8951c7e7..ddceaa9a9 100644
--- a/yt_dlp/networking/common.py
+++ b/yt_dlp/networking/common.py
@@ -206,6 +206,7 @@ class RequestHandler(abc.ABC):
     - `cookiejar`: Cookiejar to use for this request.
     - `timeout`: socket timeout to use for this request.
     - `legacy_ssl`: Enable legacy SSL options for this request. See legacy_ssl_support.
+    - `keep_header_casing`: Keep the casing of headers when sending the request.
     To enable these, add extensions.pop('<extension>', None) to _check_extensions
 
     Apart from the url protocol, proxies dict may contain the following keys:
@@ -259,6 +260,23 @@ def _make_sslcontext(self, legacy_ssl_support=None):
     def _merge_headers(self, request_headers):
         return HTTPHeaderDict(self.headers, request_headers)
 
+    def _prepare_headers(self, request: Request, headers: HTTPHeaderDict) -> None:  # noqa: B027
+        """Additional operations to prepare headers before building. To be extended by subclasses.
+        @param request: Request object
+        @param headers: Merged headers to prepare
+        """
+
+    def _get_headers(self, request: Request) -> dict[str, str]:
+        """
+        Get headers for external use.
+        Subclasses may define a _prepare_headers method to modify headers after merge but before building.
+        """
+        headers = self._merge_headers(request.headers)
+        self._prepare_headers(request, headers)
+        if request.extensions.get('keep_header_casing'):
+            return headers.sensitive()
+        return dict(headers)
+
     def _calculate_timeout(self, request):
         return float(request.extensions.get('timeout') or self.timeout)
 
@@ -317,6 +335,7 @@ def _check_extensions(self, extensions):
         assert isinstance(extensions.get('cookiejar'), (YoutubeDLCookieJar, NoneType))
         assert isinstance(extensions.get('timeout'), (float, int, NoneType))
         assert isinstance(extensions.get('legacy_ssl'), (bool, NoneType))
+        assert isinstance(extensions.get('keep_header_casing'), (bool, NoneType))
 
     def _validate(self, request):
         self._check_url_scheme(request)
diff --git a/yt_dlp/networking/impersonate.py b/yt_dlp/networking/impersonate.py
index 0626b3b49..b90d10b76 100644
--- a/yt_dlp/networking/impersonate.py
+++ b/yt_dlp/networking/impersonate.py
@@ -5,11 +5,11 @@
 from dataclasses import dataclass
 from typing import Any
 
-from .common import RequestHandler, register_preference
+from .common import RequestHandler, register_preference, Request
 from .exceptions import UnsupportedRequest
 from ..compat.types import NoneType
 from ..utils import classproperty, join_nonempty
-from ..utils.networking import std_headers
+from ..utils.networking import std_headers, HTTPHeaderDict
 
 
 @dataclass(order=True, frozen=True)
@@ -123,7 +123,17 @@ def _get_request_target(self, request):
         """Get the requested target for the request"""
         return self._resolve_target(request.extensions.get('impersonate') or self.impersonate)
 
-    def _get_impersonate_headers(self, request):
+    def _prepare_impersonate_headers(self, request: Request, headers: HTTPHeaderDict) -> None:  # noqa: B027
+        """Additional operations to prepare headers before building. To be extended by subclasses.
+        @param request: Request object
+        @param headers: Merged headers to prepare
+        """
+
+    def _get_impersonate_headers(self, request: Request) -> dict[str, str]:
+        """
+        Get headers for external impersonation use.
+        Subclasses may define a _prepare_impersonate_headers method to modify headers after merge but before building.
+        """
         headers = self._merge_headers(request.headers)
         if self._get_request_target(request) is not None:
             # remove all headers present in std_headers
@@ -131,7 +141,11 @@ def _get_impersonate_headers(self, request):
             for k, v in std_headers.items():
                 if headers.get(k) == v:
                     headers.pop(k)
-        return headers
+
+        self._prepare_impersonate_headers(request, headers)
+        if request.extensions.get('keep_header_casing'):
+            return headers.sensitive()
+        return dict(headers)
 
 
 @register_preference(ImpersonateRequestHandler)
diff --git a/yt_dlp/utils/networking.py b/yt_dlp/utils/networking.py
index 933b164be..542abace8 100644
--- a/yt_dlp/utils/networking.py
+++ b/yt_dlp/utils/networking.py
@@ -1,9 +1,16 @@
+from __future__ import annotations
+
 import collections
+import collections.abc
 import random
+import typing
 import urllib.parse
 import urllib.request
 
-from ._utils import remove_start
+if typing.TYPE_CHECKING:
+    T = typing.TypeVar('T')
+
+from ._utils import NO_DEFAULT, remove_start
 
 
 def random_user_agent():
@@ -51,32 +58,141 @@ def random_user_agent():
     return _USER_AGENT_TPL % random.choice(_CHROME_VERSIONS)
 
 
-class HTTPHeaderDict(collections.UserDict, dict):
+class HTTPHeaderDict(dict):
     """
     Store and access keys case-insensitively.
     The constructor can take multiple dicts, in which keys in the latter are prioritised.
+
+    Retains a case sensitive mapping of the headers, which can be accessed via `.sensitive()`.
     """
+    def __new__(cls, *args: typing.Any, **kwargs: typing.Any) -> typing.Self:
+        obj = dict.__new__(cls, *args, **kwargs)
+        obj.__sensitive_map = {}
+        return obj
 
-    def __init__(self, *args, **kwargs):
+    def __init__(self, /, *args, **kwargs):
         super().__init__()
-        for dct in args:
-            if dct is not None:
-                self.update(dct)
-        self.update(kwargs)
+        self.__sensitive_map = {}
+
+        for dct in filter(None, args):
+            self.update(dct)
+        if kwargs:
+            self.update(kwargs)
+
+    def sensitive(self, /) -> dict[str, str]:
+        return {
+            self.__sensitive_map[key]: value
+            for key, value in self.items()
+        }
+
+    def __contains__(self, key: str, /) -> bool:
+        return super().__contains__(key.title() if isinstance(key, str) else key)
+
+    def __delitem__(self, key: str, /) -> None:
+        key = key.title()
+        del self.__sensitive_map[key]
+        super().__delitem__(key)
 
-    def __setitem__(self, key, value):
+    def __getitem__(self, key, /) -> str:
+        return super().__getitem__(key.title())
+
+    def __ior__(self, other, /):
+        if isinstance(other, type(self)):
+            other = other.sensitive()
+        if isinstance(other, dict):
+            self.update(other)
+            return
+        return NotImplemented
+
+    def __or__(self, other, /) -> typing.Self:
+        if isinstance(other, type(self)):
+            other = other.sensitive()
+        if isinstance(other, dict):
+            return type(self)(self.sensitive(), other)
+        return NotImplemented
+
+    def __ror__(self, other, /) -> typing.Self:
+        if isinstance(other, type(self)):
+            other = other.sensitive()
+        if isinstance(other, dict):
+            return type(self)(other, self.sensitive())
+        return NotImplemented
+
+    def __setitem__(self, key: str, value, /) -> None:
         if isinstance(value, bytes):
             value = value.decode('latin-1')
-        super().__setitem__(key.title(), str(value).strip())
+        key_title = key.title()
+        self.__sensitive_map[key_title] = key
+        super().__setitem__(key_title, str(value).strip())
 
-    def __getitem__(self, key):
-        return super().__getitem__(key.title())
+    def clear(self, /) -> None:
+        self.__sensitive_map.clear()
+        super().clear()
 
-    def __delitem__(self, key):
-        super().__delitem__(key.title())
+    def copy(self, /) -> typing.Self:
+        return type(self)(self.sensitive())
 
-    def __contains__(self, key):
-        return super().__contains__(key.title() if isinstance(key, str) else key)
+    @typing.overload
+    def get(self, key: str, /) -> str | None: ...
+
+    @typing.overload
+    def get(self, key: str, /, default: T) -> str | T: ...
+
+    def get(self, key, /, default=NO_DEFAULT):
+        key = key.title()
+        if default is NO_DEFAULT:
+            return super().get(key)
+        return super().get(key, default)
+
+    @typing.overload
+    def pop(self, key: str, /) -> str: ...
+
+    @typing.overload
+    def pop(self, key: str, /, default: T) -> str | T: ...
+
+    def pop(self, key, /, default=NO_DEFAULT):
+        key = key.title()
+        if default is NO_DEFAULT:
+            self.__sensitive_map.pop(key)
+            return super().pop(key)
+        self.__sensitive_map.pop(key, default)
+        return super().pop(key, default)
+
+    def popitem(self) -> tuple[str, str]:
+        self.__sensitive_map.popitem()
+        return super().popitem()
+
+    @typing.overload
+    def setdefault(self, key: str, /) -> str: ...
+
+    @typing.overload
+    def setdefault(self, key: str, /, default) -> str: ...
+
+    def setdefault(self, key, /, default=None) -> str:
+        key = key.title()
+        if key in self.__sensitive_map:
+            return super().__getitem__(key)
+
+        self[key] = default or ''
+        return self[key]
+
+    def update(self, other, /, **kwargs) -> None:
+        if isinstance(other, type(self)):
+            other = other.sensitive()
+        if isinstance(other, collections.abc.Mapping):
+            for key, value in other.items():
+                self[key] = value
+
+        elif hasattr(other, 'keys'):
+            for key in other.keys():  # noqa: SIM118
+                self[key] = other[key]
+
+        else:
+            for key, value in other:
+                self[key] = value
+
+        for key, value in kwargs.items():
+            self[key] = value
 
 
 std_headers = HTTPHeaderDict({


Test patch:
diff --git a/test/test_networking.py b/test/test_networking.py
index d96624af1..63914bc4b 100644
--- a/test/test_networking.py
+++ b/test/test_networking.py
@@ -720,6 +720,15 @@ def test_allproxy(self, handler):
                     rh, Request(
                         f'http://127.0.0.1:{self.http_port}/headers', proxies={'all': 'http://10.255.255.255'})).close()
 
+    @pytest.mark.skip_handlers_if(lambda _, handler: handler not in ['Urllib', 'CurlCFFI'], 'handler does not support keep_header_casing')
+    def test_keep_header_casing(self, handler):
+        with handler() as rh:
+            res = validate_and_send(
+                rh, Request(
+                    f'http://127.0.0.1:{self.http_port}/headers', headers={'X-test-heaDer': 'test'}, extensions={'keep_header_casing': True})).read().decode()
+
+            assert 'X-test-heaDer: test' in res
+
 
 @pytest.mark.parametrize('handler', ['Urllib', 'Requests', 'CurlCFFI'], indirect=True)
 class TestClientCertificate:
@@ -1289,6 +1298,7 @@ class HTTPSupportedRH(ValidationRH):
             ({'legacy_ssl': False}, False),
             ({'legacy_ssl': True}, False),
             ({'legacy_ssl': 'notabool'}, AssertionError),
+            ({'keep_header_casing': True}, UnsupportedRequest),
         ]),
         ('Requests', 'http', [
             ({'cookiejar': 'notacookiejar'}, AssertionError),
@@ -1299,6 +1309,9 @@ class HTTPSupportedRH(ValidationRH):
             ({'legacy_ssl': False}, False),
             ({'legacy_ssl': True}, False),
             ({'legacy_ssl': 'notabool'}, AssertionError),
+            ({'keep_header_casing': False}, False),
+            ({'keep_header_casing': True}, False),
+            ({'keep_header_casing': 'notabool'}, AssertionError),
         ]),
         ('CurlCFFI', 'http', [
             ({'cookiejar': 'notacookiejar'}, AssertionError),
diff --git a/test/test_utils.py b/test/test_utils.py
index 8f81d0b1b..65f28db36 100644
--- a/test/test_utils.py
+++ b/test/test_utils.py
@@ -3,19 +3,20 @@
 # Allow direct execution
 import os
 import sys
-import unittest
-import unittest.mock
-import warnings
-import datetime as dt
 
 sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
 
 
 import contextlib
+import datetime as dt
 import io
 import itertools
 import json
+import pickle
 import subprocess
+import unittest
+import unittest.mock
+import warnings
 import xml.etree.ElementTree
 
 from yt_dlp.compat import (
@@ -2087,21 +2088,26 @@ def test_http_header_dict(self):
         headers = HTTPHeaderDict()
         headers['ytdl-test'] = b'0'
         self.assertEqual(list(headers.items()), [('Ytdl-Test', '0')])
+        self.assertEqual(list(headers.sensitive().items()), [('ytdl-test', '0')])
         headers['ytdl-test'] = 1
         self.assertEqual(list(headers.items()), [('Ytdl-Test', '1')])
+        self.assertEqual(list(headers.sensitive().items()), [('ytdl-test', '1')])
         headers['Ytdl-test'] = '2'
         self.assertEqual(list(headers.items()), [('Ytdl-Test', '2')])
+        self.assertEqual(list(headers.sensitive().items()), [('Ytdl-test', '2')])
         self.assertTrue('ytDl-Test' in headers)
         self.assertEqual(str(headers), str(dict(headers)))
         self.assertEqual(repr(headers), str(dict(headers)))
 
         headers.update({'X-dlp': 'data'})
         self.assertEqual(set(headers.items()), {('Ytdl-Test', '2'), ('X-Dlp', 'data')})
+        self.assertEqual(set(headers.sensitive().items()), {('Ytdl-test', '2'), ('X-dlp', 'data')})
         self.assertEqual(dict(headers), {'Ytdl-Test': '2', 'X-Dlp': 'data'})
         self.assertEqual(len(headers), 2)
         self.assertEqual(headers.copy(), headers)
-        headers2 = HTTPHeaderDict({'X-dlp': 'data3'}, **headers, **{'X-dlp': 'data2'})
+        headers2 = HTTPHeaderDict({'X-dlp': 'data3'}, headers, **{'X-dlP': 'data2'})
         self.assertEqual(set(headers2.items()), {('Ytdl-Test', '2'), ('X-Dlp', 'data2')})
+        self.assertEqual(set(headers2.sensitive().items()), {('Ytdl-test', '2'), ('X-dlP', 'data2')})
         self.assertEqual(len(headers2), 2)
         headers2.clear()
         self.assertEqual(len(headers2), 0)
@@ -2109,16 +2115,23 @@ def test_http_header_dict(self):
         # ensure we prefer latter headers
         headers3 = HTTPHeaderDict({'Ytdl-TeSt': 1}, {'Ytdl-test': 2})
         self.assertEqual(set(headers3.items()), {('Ytdl-Test', '2')})
+        self.assertEqual(set(headers3.sensitive().items()), {('Ytdl-test', '2')})
         del headers3['ytdl-tesT']
         self.assertEqual(dict(headers3), {})
 
         headers4 = HTTPHeaderDict({'ytdl-test': 'data;'})
         self.assertEqual(set(headers4.items()), {('Ytdl-Test', 'data;')})
+        self.assertEqual(set(headers4.sensitive().items()), {('ytdl-test', 'data;')})
 
         # common mistake: strip whitespace from values
         # https://github.com/yt-dlp/yt-dlp/issues/8729
         headers5 = HTTPHeaderDict({'ytdl-test': ' data; '})
         self.assertEqual(set(headers5.items()), {('Ytdl-Test', 'data;')})
+        self.assertEqual(set(headers5.sensitive().items()), {('ytdl-test', 'data;')})
+
+        # test if picklable
+        headers6 = HTTPHeaderDict(a=1, b=2)
+        self.assertEqual(pickle.loads(pickle.dumps(headers6)), headers6)
 
     def test_extract_basic_auth(self):
         assert extract_basic_auth('http://:foo.bar') == ('http://:foo.bar', None)
diff --git a/test/test_websockets.py b/test/test_websockets.py
index 06112cc0b..dead5fe5c 100644
--- a/test/test_websockets.py
+++ b/test/test_websockets.py
@@ -44,7 +44,7 @@ def websocket_handler(websocket):
                 return websocket.send('2')
         elif isinstance(message, str):
             if message == 'headers':
-                return websocket.send(json.dumps(dict(websocket.request.headers)))
+                return websocket.send(json.dumps(dict(websocket.request.headers.raw_items())))
             elif message == 'path':
                 return websocket.send(websocket.request.path)
             elif message == 'source_address':
@@ -266,18 +266,18 @@ def test_cookies(self, handler):
         with handler(cookiejar=cookiejar) as rh:
             ws = ws_validate_and_send(rh, Request(self.ws_base_url))
             ws.send('headers')
-            assert json.loads(ws.recv())['cookie'] == 'test=ytdlp'
+            assert HTTPHeaderDict(json.loads(ws.recv()))['cookie'] == 'test=ytdlp'
             ws.close()
 
         with handler() as rh:
             ws = ws_validate_and_send(rh, Request(self.ws_base_url))
             ws.send('headers')
-            assert 'cookie' not in json.loads(ws.recv())
+            assert 'cookie' not in HTTPHeaderDict(json.loads(ws.recv()))
             ws.close()
 
             ws = ws_validate_and_send(rh, Request(self.ws_base_url, extensions={'cookiejar': cookiejar}))
             ws.send('headers')
-            assert json.loads(ws.recv())['cookie'] == 'test=ytdlp'
+            assert HTTPHeaderDict(json.loads(ws.recv()))['cookie'] == 'test=ytdlp'
             ws.close()
 
     @pytest.mark.skip_handler('Websockets', 'Set-Cookie not supported by websockets')
@@ -287,7 +287,7 @@ def test_cookie_sync_only_cookiejar(self, handler):
             ws_validate_and_send(rh, Request(f'{self.ws_base_url}/get_cookie', extensions={'cookiejar': YoutubeDLCookieJar()}))
             ws = ws_validate_and_send(rh, Request(self.ws_base_url, extensions={'cookiejar': YoutubeDLCookieJar()}))
             ws.send('headers')
-            assert 'cookie' not in json.loads(ws.recv())
+            assert 'cookie' not in HTTPHeaderDict(json.loads(ws.recv()))
             ws.close()
 
     @pytest.mark.skip_handler('Websockets', 'Set-Cookie not supported by websockets')
@@ -298,12 +298,12 @@ def test_cookie_sync_delete_cookie(self, handler):
             ws_validate_and_send(rh, Request(f'{self.ws_base_url}/get_cookie'))
             ws = ws_validate_and_send(rh, Request(self.ws_base_url))
             ws.send('headers')
-            assert json.loads(ws.recv())['cookie'] == 'test=ytdlp'
+            assert HTTPHeaderDict(json.loads(ws.recv()))['cookie'] == 'test=ytdlp'
             ws.close()
             cookiejar.clear_session_cookies()
             ws = ws_validate_and_send(rh, Request(self.ws_base_url))
             ws.send('headers')
-            assert 'cookie' not in json.loads(ws.recv())
+            assert 'cookie' not in HTTPHeaderDict(json.loads(ws.recv()))
             ws.close()
 
     def test_source_address(self, handler):
@@ -341,6 +341,14 @@ def test_request_headers(self, handler):
             assert headers['test3'] == 'test3'
             ws.close()
 
+    def test_keep_header_casing(self, handler):
+        with handler(headers=HTTPHeaderDict({'x-TeSt1': 'test'})) as rh:
+            ws = ws_validate_and_send(rh, Request(self.ws_base_url, headers={'x-TeSt2': 'test'}, extensions={'keep_header_casing': True}))
+            ws.send('headers')
+            headers = json.loads(ws.recv())
+            assert 'x-TeSt1' in headers
+            assert 'x-TeSt2' in headers
+
     @pytest.mark.parametrize('client_cert', (
         {'client_certificate': os.path.join(MTLS_CERT_DIR, 'clientwithkey.crt')},
         {