Repository: yt-dlp
Issue: ATV throws KeyError start error for older videos (?)
Labels: site-bug,patch-available

### DO NOT REMOVE OR SKIP THE ISSUE TEMPLATE

- [X] I understand that I will be **blocked** if I *intentionally* remove or skip any mandatory\* field

### Checklist

- [X] I'm reporting that yt-dlp is broken on a **supported** site
- [X] I've verified that I'm running yt-dlp version **2023.07.06** ([update instructions](https://github.com/yt-dlp/yt-dlp#update)) or later (specify commit)
- [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) and the [bugtracker](https://github.com/yt-dlp/yt-dlp/issues?q=) for similar issues **including closed ones**. DO NOT post duplicates
- [X] I've read the [guidelines for opening an issue](https://github.com/yt-dlp/yt-dlp/blob/master/CONTRIBUTING.md#opening-an-issue)
- [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

Austria

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

When I try downloading older videos from the ATV site, I get a "An extractor error has occurred. (caused by KeyError('start')); please report this issue..." for some videos (others just work). So that's what I'm doing :-)

### 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://atv.at/tv/amore-unter-palmen/staffel-02/episode-02/folge-2-stress-in-tunesien"
[debug] Command-line config: ['-vU', ' https://atv.at/tv/amore-unter-palmen/staffel-02/episode-02/folge-2-stress-in-tunesien']
[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@2023.07.06 [b532a3481] (pip)
[debug] Python 3.9.2 (CPython armv7l 32bit) - Linux-5.15.36-v7l+-armv7l-with-glibc2.31 (OpenSSL 1.1.1n  15 Mar 2022, glibc 2.31)
[debug] exe versions: ffmpeg 4.3.4-0, ffprobe 4.3.4-0, phantomjs broken
[debug] Optional libraries: Cryptodome-3.9.7, brotli-1.0.9, certifi-2020.06.20, mutagen-1.45.1, secretstorage-3.3.1, sqlite3-2.6.0, websockets-10.3
[debug] Proxy map: {}
[debug] Loaded 1855 extractors
[debug] Fetching release info: https://api.github.com/repos/yt-dlp/yt-dlp/releases/latest
Available version: stable@2023.07.06, Current version: stable@2023.07.06
yt-dlp is up to date (stable@2023.07.06)
[ATVAt] Extracting URL: https://atv.at/tv/amore-unter-palmen/staffel-02/episode-02/folge-2-stress-in-tunesien
[ATVAt] folge-2-stress-in-tunesien: Downloading webpage
ERROR: folge-2-stress-in-tunesien: An extractor error has occurred. (caused by KeyError('start')); 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 "/home/servant/.local/lib/python3.9/site-packages/yt_dlp/extractor/common.py", line 710, in extract
    ie_result = self._real_extract(url)
  File "/home/servant/.local/lib/python3.9/site-packages/yt_dlp/extractor/atvat.py", line 71, in _real_extract
    content_ids = [{'id': id, 'subclip_start': content['start'], 'subclip_end': content['end']}
  File "/home/servant/.local/lib/python3.9/site-packages/yt_dlp/extractor/atvat.py", line 71, in <listcomp>
    content_ids = [{'id': id, 'subclip_start': content['start'], 'subclip_end': content['end']}
KeyError: 'start'
```