I have seen several videos which show as archived, and video metadata does show up, but the video itself doesn’t with a magic error hacked into the rendered page:
Sorry the Wayback Machine does not have this video (<id>) archived (or not indexed yet).
So does this message indicate:
I did however find some videos that still work, e.g.: https://web.archive.org/web/2oe_/http://wayback-fakeurl.archive.org/yt/d81mEbL8Yw8 but it’s just too unreliable, I can’t predict which ones will work and which ones won’t.
So for now I’ll have to stick to https://github.com/ytdl-org/youtube-dl + reupload when I find a hot video I want to archive.