Sounds like fake files! Search again, vary your search terms, try the All Types search. Stay away from files with lots of sources, go for a file with 10 sources or less, or those with a modem source.
Always check a video file before download with Bitzi. Files with heaps of sources but no Bitzi rating are often fakes.
How to use Bitzi

Also some tips & info about these fakes
Info about fake files