There a lot of corrupted, infected, or fake files on the network. It is not a good idea to go for files hosted by high numbers of hosts 50-100 or more.
Video files (as well as others, but not so frequently) can be checked with Bitzi (right click on a file in the search window, and go to Advanced>Look up with Bitzi) and you will go to a Website which rates the file if it has been reviewed)
Try downloading files with single Modem hosts once or twice, as they tend to be good.
I'm just checking you have really checked to see if everything is coming up corupt.
If none of this helps, please let us know some details of your set up etc.
