Repository: ytdl-org/youtube-dl

Issue:
[slideslive.com] add support
Here is an example video (+slides)
https://slideslive.com/38891225/tri-urovne-motoriky



Discussion:
I have found this code snippet in the webpage source which contains directly a youtube video code (externalMediaID), but I guess their player is able to play video from different sources.

 var playerRequiredParameters = {
                    playerPath: "//d2ygwrecguqg66.cloudfront.net/assets/Player_5_THC-70ce1e5ead496b3126c5309b56c9f075.swf",
                    videoType: 98,
                    hasVideo: "true",
                    hasSlides: "true",
                    presentationID: "38891225",
                    internalMediaType: "YOUTUBE",
                    internalMediaID: "H_TXnKQ2pBU",
                    externalMediaType: "YOUTUBE",
                    externalMediaID: "SM45wcmVg2o",
                    isPaid: "false",
                    secureProtocol: "true",
                    lastUpdated: "1396565784",
                    startSlide: 1,
                    startTime: 0,
                    html5: 0
                };

Would downloading the YouTube video be sufficient here?

All videos I have checked so far (around 10) was from youtube, but I will investigate more. 

Sorry, that's not what I meant. I meant: is having only the YouTube video (and not the slides) sufficient?

I guess. I mean it would be nice to have the slides too, but the time synchronization will be lost in any case, right?

I noticed that a request like this is enough to get the Youtube watch parameter:

    $ curl -s 'https://slideslive.com/38902354?demo=false' -H 'Accept: application/json, text/javascript, */*; q=0.01' -H 'X-Requested-With: XMLHttpRequest'

Resolving patch:
diff --git a/youtube_dl/extractor/extractors.py b/youtube_dl/extractor/extractors.py
--- a/youtube_dl/extractor/extractors.py
+++ b/youtube_dl/extractor/extractors.py
@@ -943,6 +943,7 @@
 )
 from .skysports import SkySportsIE
 from .slideshare import SlideshareIE
+from .slideslive import SlidesLiveIE
 from .slutload import SlutloadIE
 from .smotri import (
     SmotriIE,
diff --git a/youtube_dl/extractor/slideslive.py b/youtube_dl/extractor/slideslive.py
new file mode 100644
--- /dev/null
+++ b/youtube_dl/extractor/slideslive.py
@@ -0,0 +1,34 @@
+# coding: utf-8
+from __future__ import unicode_literals
+
+from .common import InfoExtractor
+from ..utils import ExtractorError
+
+
+class SlidesLiveIE(InfoExtractor):
+    _VALID_URL = r'https?://slideslive\.com/(?P<id>[0-9]+)'
+    _TESTS = [{
+        'url': 'https://slideslive.com/38902413/gcc-ia16-backend',
+        'md5': 'b29fcd6c6952d0c79c5079b0e7a07e6f',
+        'info_dict': {
+            'id': 'LMtgR8ba0b0',
+            'ext': 'mp4',
+            'title': '38902413: external video',
+            'description': '3890241320170925-9-1yd6ech.mp4',
+            'uploader': 'SlidesLive Administrator',
+            'uploader_id': 'UC62SdArr41t_-_fX40QCLRw',
+            'upload_date': '20170925',
+        }
+    }]
+
+    def _real_extract(self, url):
+        video_id = self._match_id(url)
+        video_data = self._download_json(
+            url, video_id, headers={'Accept': 'application/json'})
+        service_name = video_data['video_service_name']
+        if service_name == 'YOUTUBE':
+            yt_video_id = video_data['video_service_id']
+            return self.url_result(yt_video_id, 'Youtube', video_id=yt_video_id)
+        else:
+            raise ExtractorError(
+                'Unsupported service name: {0}'.format(service_name), expected=True)


Test patch: