They could be mpeg1/4 files. Mpeg 1 is used for VCD, mpeg2 for svcd & dvd, mpeg4 can be used for vcd (I think, I've never tried.) However the other day I dropped a divx-avi file into Roxio Toast (mac) & it had no probs recognising it to burn. (divx is equivalent to mpeg4.)
Are you able to play these files on your computer? If not, you're either missing codecs to play/convert/burn or the file's corrupt. Else, the file was converted in an odd way - thus needing a particular codec else it's as good as corrupt.

Roxio also offer CD/DVD Creator for windows which I would go as far to say is better than Nero (I've tried both.) This app will convert to the necessary format if it's in avi/mpeg, etc.