I've been trying to figure this out. I have a project that uses flv's in it, I've worked on another machine (mac os x, ae cs 5.5 - both comps the same), but I'm unable to open it on the current comp I'm using. It says After Effects error, flv file not supported or damaged. I am sure the files are not damaged and it will open on another machine, but I need it to work on mine!
Note- I also can't play/preview flv's in general on the computer, so I'm wondering where the issue lies..