There is much discussion about codecs and formats that aren't supported (yet) by Lightworks.
As a workaround I would suggest to transcode the movie files with VirtualDub, Avidemux or a similar software. I know it takes time, but it could help to test/learn LW or for smaller projects.
So, what do you think, which formats work best on LW? What software, codecs and settings did you use to recode your movie files?
BTW, as a matter of fact I have my videos in H.264 MOV format (LW doesn't really like them), and I ould like to transcode them in another compressed format, if possible (I'm quite low on hard disk space right now).