Most old OGYouTube versions don't seem to be preserved on third party websites or the Wayback Machine. If possible, maybe set up a mirror on Internet Archive of all the versions you still have.
Especially versions dating back to YouTube v4 are barely archived. I only found a single archive of an OGYouTube Version based on v4, and it was an unofficial modified version.
Most old OGYouTube versions don't seem to be preserved on third party websites or the Wayback Machine. If possible, maybe set up a mirror on Internet Archive of all the versions you still have.
Especially versions dating back to YouTube v4 are barely archived. I only found a single archive of an OGYouTube Version based on v4, and it was an unofficial modified version.