How large is the file? HD video is very large & if the person who converted it had problems with their computer reading it or poor conversion tools might have resulted in the out of synch.

I downlded part of one last year & didn't have problems playing it. But that was on a mac.
Alternatives? MPlayer perhaps ... MPlayer is similar to VLC with in-built codecs but ... you can still add more to it such as Real file abilities but need to obtain such plug-ins separately afaik - reallib codecs (presumably for legal/copyright reasons.) http://www.mplayerhq.hu/design7/dload.html. You could also check http://forms.helixcommunity.org/helix/builds/