Also just as a test, try d/loading a video from here:
http://www.magnetmix.com/video.shtml. Try the first episode of "The Scene". It'll open up in LW. If it says "Needs More Sources", right click the file and click "Find More Sources".
If it d/loads, then the files you've been trying to d/load were prolly fake and you should refer to the link that
muhctekdano left in his post.
Another tip is to look up the files with
Bitzi Web Lookup to see if they have been rated before downloading. Chances are pretty good that if noone has rated them that they are fake.
Try the tips in this thread(also applies to vidieos):
How to find music 