first i thought to be flash, but seems that flash is a old tec now a days.

or they keep the uploader video file format?

as nobody can see the format on their page.

  • 1
    Youtube uses HTML5 since a long time ago.
    – user171700
    Commented Apr 29, 2018 at 23:12
  • 1
    If you copy the URL of a YouTube video to VLC, then you can see the details of the codec with Ctrl-J. The codec information is also accessible through the tools menu when not in full screen.
    – AFH
    Commented Apr 29, 2018 at 23:19
  • 3
    This answer seems to have all the info you are looking for: video.stackexchange.com/questions/5318/…
    – Narzard
    Commented Apr 29, 2018 at 23:29

1 Answer 1


Actually you can see the format (at least codecs) on their page. Right click on video player and select Stats for nerds.

Screenshot of YouTube stats for nerds

As you can see the Codecs are vp9 and opus. If you want to know the actual format (container), please refer to the list below. In this example its a .webm file.

YouTube uses multiple formats for playback in various types of devices. Here they are based on priority.

  1. WEBM
    Google loves their VP9 codec. So, If it's a modern browser and supports WEBM playback and has the CPU resorces to decode VP9 it will use WEBM format.

    • Video codec: VP9 or sometimes VP8
    • Audio codec: Opus
  2. MP4
    It's for the all other modern browsers that supports HTML5 video. The MP4 container have:

    • Video codec: MPEG-4 Part 10 aka h.264
    • Audio codec: AAC
  3. FLV
    Although it has announces the end of flash it still .flv files for older browsers and devices and will discontinue soon. The flv files are below 720p.

  4. 3GP
    This format are for older mobile devices and only available in 240p and 144p. This container have:

    • Video codec: MPEG-4 Part 2
    • Audio codec: AAC
  • Note that YouTube uses independent audio and video streams most of the time (i.e. when DASH is supported), so you'll usually have two containers, e.g. webm(vp9) and webm(opus). And although it's been a while since I checked, I think they don't even have a merged webm(vp9+opus) anymore. (They still have mp4(h264+aac) for compatibility though.)
    – user1686
    Commented Apr 30, 2018 at 3:56
  • Hmm. Almost all the time there's no sudo in 1080p video.
    – BorhnN
    Commented Apr 30, 2018 at 4:00

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