You can get a rough idea of how big each video is via an activitypub query for each video. For example:
curl --header 'accept: application/activity+json' https://peertube.wtf/w/mhghLtY5dkLguNq5oFB2Ut | jq .
Buried in there is a url entry, and buried in some of those is a tag entry and buried in some of those are details for the size of the video and audio for each upload.
Peertube’s video channels have an outbox (similar to how Lemmy’s communities do, but not limited to 50 entries), so you can step through that to find the relevant info for everything in your channel.
Doing that for your channel, I got:
Shitpost #2
video: 482 x 480: 2.27 MB
audio: 0.3 MB
Shitpost #1
video: 480 x 480: 8.69 MB
audio: 0.94 MB
Will this replace the internet?
video: 1080 x 1920: 19.26 MB
video: 720 x 1280: 11.9 MB
video: 360 x 640: 5.23 MB
audio: 16.75 MB
Cat
video: 1920 x 1080: 7.77 MB
video: 1280 x 720: 2.14 MB
video: 640 x 360: 0.41 MB
audio: 0.23 MB
If you assume that the size of the audio is ignored, and that lower resolutions are transcoded as requested, and add the sizes for the highest resolutions together, you get 2.27 + 8.69 + 19.26 + 7.77 = 37.99 (which is the 38 MB visible in your screenshot).
The information is available, but it’s a pain in the arse to get, so it’s probably annoying for PeerTube themselves to show (a brief look suggests that the API response doesn’t provide it, so there’s nothing for the web frontend to display). It’s also possible that they may drop the higher resolutions for videos with low engagement, so the size of each upload isn’t static, which adds an extra complication.
