Wasn't too sure if I should make a thread on this, since he doesn't give too much info on the videos, but maybe someone might find it interesting.
Oddheader is a youtube channel that mostly documents odd and obscure glitches and findings in video games. At around 11:29 of his video "10 Creepiest Unexplained Glitches in Video Games" he mentions having glitch videos on the site Mythica.com and to contact him if they were found. No other information given in the video sadly. Unsure if any updates since I don't use twitter and am not part of his discord. The video where he mentions the lost mythica videos can be seen here:
If anything, this could also become a hub for mythica content in general, but mainly oddheader's comment got me interested as I am a big fan of his content.