$ yt-dlp -F 'https://www.youtube.com/watch?v=xC5uEe5OzNQ'
  [youtube] xC5uEe5OzNQ: Downloading webpage
  [youtube] xC5uEe5OzNQ: Downloading android player API JSON
  [info] Available formats for xC5uEe5OzNQ:
  ID  EXT   RESOLUTION FPS │    FILESIZE  TBR PROTO │ VCODEC       VBR ACODEC      ABR     ASR MORE INFO
  ───────────────────────────────────────────────────────────────────────────────────────────────────────────────
  sb2 mhtml 48x27          │                  mhtml │ images                                   storyboard
  sb1 mhtml 60x45          │                  mhtml │ images                                   storyboard
  sb0 mhtml 120x90         │                  mhtml │ images                                   storyboard
  139 m4a                  │     1.55MiB  47k https │ audio only       mp4a.40.5   47k 22050Hz low, m4a_dash
  140 m4a                  │     4.13MiB 127k https │ audio only       mp4a.40.2  127k 44100Hz medium, m4a_dash
  251 webm                 │     4.11MiB 126k https │ audio only       opus       126k 48000Hz medium, webm_dash
  17  3gp   176x144      8 │     2.67MiB  82k https │ mp4v.20.3    82k mp4a.40.2    0k 22050Hz 144p
  160 mp4   192x144     25 │  1006.62KiB  30k https │ avc1.4d400b  30k video only              144p, mp4_dash
  278 webm  192x144     25 │     1.70MiB  52k https │ vp9          52k video only              144p, webm_dash
  133 mp4   320x240     25 │     2.01MiB  61k https │ avc1.4d400d  61k video only              240p, mp4_dash
  18  mp4   320x240     25 │     9.42MiB 290k https │ avc1.42001E 290k mp4a.40.2    0k 44100Hz 240p
  242 webm  320x240     25 │     2.81MiB  86k https │ vp9          86k video only              240p, webm_dash

None of these will be the format it was originally uploaded in, but I’d guess format 133 (~61 kbps) to be the closest for the video part, at 2MB. Judging by the sound of it, the original audio bit rate was probably higher than the video bit rate!