[groks]

    $ youtube-dl --list-formats https://www.youtube.com/watch?v=DeJLzyxZqbk | grep '[0-9]x[0-9]'
    278          webm       256x144    DASH video   93k , webm container, vp9, 24fps, video only, 1.09MiB
    242          webm       426x240    DASH video  110k , vp9, 24fps, video only, 1.00MiB
    160          mp4        256x144    DASH video  113k , avc1.4d400c, 24fps, video only, 1.41MiB
    243          webm       640x360    DASH video  196k , vp9, 24fps, video only, 1.83MiB
    133          mp4        426x240    DASH video  247k , avc1.4d4015, 24fps, video only, 3.08MiB
    134          mp4        640x360    DASH video  263k , avc1.4d401e, 24fps, video only, 2.95MiB
    244          webm       854x480    DASH video  322k , vp9, 24fps, video only, 3.11MiB
    135          mp4        854x480    DASH video  554k , avc1.4d401e, 24fps, video only, 6.30MiB
    247          webm       1280x720   DASH video  714k , vp9, 24fps, video only, 7.48MiB
    136          mp4        1280x720   DASH video 1127k , avc1.4d401f, 24fps, video only, 12.92MiB
    248          webm       1920x1080  DASH video 1579k , vp9, 24fps, video only, 17.86MiB
    137          mp4        1920x1080  DASH video 2304k , avc1.640028, 24fps, video only, 27.09MiB
    17           3gp        176x144    small , mp4v.20.3,  mp4a.40.2@ 24k
    36           3gp        320x180    small , mp4v.20.3,  mp4a.40.2
    18           mp4        640x360    medium , avc1.42001E,  mp4a.40.2@ 96k
    43           webm       640x360    medium , vp8.0,  vorbis@128k
    22           mp4        1280x720   hd720 , avc1.64001F,  mp4a.40.2@192k (best)