[Bug] Change fileformat for vp9 videos to .webm

[thibaultmol]

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• Tried latest version

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• This issue is not duplicated with any other open or closed issues

Describe the bug

Something I've noticed is that videos download from facebook video/Reels often result in a .mp4 which then contains a vp90 video stream and an AAC audio stream. but apperentally having vp9(0) in an .mp4 is uncommon and so various apps like telegram, signal etc. ... don't recognize it as a proper video file and refuse to play it just send it as a file instead of a video.
Having it save as a .webm file (which at this point also plays on pretty much any device) would fix this I think

Expected behavior

No response

Steps to reproduce

1. Download any facebook reel/video
2. try to share the file to a contact via signal/telegram etc

Device information

Fairphone 5
android 14

Screenshots / Recordings

No response

Additional context

No response

[deniscerri]

If your container preference is default, this is how yt-dlp chooses to save the file as so you need to open the issue to them. If your container preference is mp4, then make it default instead.

[thibaultmol]

sorry, I don't think we're on the same page.
So my yt-dlnis is set to use default. But either way.... seems like yt-dlp on desktop also saves it as .mp4 when using a facebook reel url... so guess it's their fault or something. i dunno. it's fine