pacman.a26 would be the rom name (or perhaps pacman.bin). The preview movie I see resembles pac-man, but is not the 'atari 2600' original pac-man by tod frye.
Btw, I have no issue changing the preview video (for myself), but thought it was maybe a general emumovies issue.
I also think Dintar's pac-man should have an official entry in emumovies. You can find it on Atariage. It is a homebrew not released on cart yet. Best pac-man past or present for atari 2600. It is simply incredible.