For movies probably avi, mpg/mpeg are the best ones. Others like wmv, mov, asf, ect tend to be spam, porn, and whatnot. Check files with
Bitzi Web Lookup before downloading. It'll help you sort out if it's a good file or not. Also preview the file when it gets to 10% to check it's what the title says.
See this thread for tips on searching and downloading files.
How to find music(same principles apply to movies).
BTW: This is the BearShare Forum. From your other post i take you should be using the LimeWire forum.
LimeWire (Cross-platform) 
.