Older hardware or software (like older versions of QuickTime) may struggle to play VP9 video, even inside an MP4 container.
Because it is a DASH (Dynamic Adaptive Streaming over HTTP) stream, it contains no audio. If you download it by itself, you will have a silent video. How to Download 609 with Audio 609 mp4
If you download only Format 609, your player might show a black screen or play without sound. Always remember to use the + syntax to add an audio ID. Older hardware or software (like older versions of
Format ID 609 is a YouTube-specific stream identifier. Its technical specs usually look like this: 1280x720 (720p) Container: MP4 Codec: vp09 (VP9) Type: Video-only How to Download 609 with Audio If you
While VP9 is typically associated with WebM, Format 609 wraps it in an MP4 container, which can be useful for certain modern media players that prefer the MP4 extension but support the VP9 codec. Common Issues
To get a functional video file, you must merge Format 609 with an audio stream (like Format 140, which is standard M4A audio). Using the command line tool yt-dlp , you would use the following command: yt-dlp -f 609+140 [VIDEO_URL]