There are lots of fake files around, these will sit connecting for ages & then get stuck needing sources forever

Always use Bitzi to check a file before download. People use Bitzi to rate files...if the file's been rated then you'll get an idea of content & quality. It's very helpful with weeding out fake & misnamed files. See the 'how to use Bitzi' link for info about downloading Bitcollider...so that you can rate files yourself.
If a file has heaps of sources but no Bitzi rating, chances are it's a fake. There's more info & tips in the threads below.
How to use Bitzi
Fake files showing up in search results
How to find music(tips for movies, too)

If a file has a good rating on Bitzi, or if you want to take a chance on an unrated file, preview the file after ~10% - 15% download...just to check.

Stay away from .exe, .rar, .wmv, .zip, & .mov files. Check file sizes...if a file looks suspiciously small then avoid it! A movie's generally 600 - 800 MB or larger.
mov files
What you should know about WMA Files

This should also help!
Direct instructions to eliminate porn from results