I am having this problem too!! How do i solve it?
The link above is dead!
Welcome to the forum.
As mentioned, all things MPEG-2 are disabled in the trial. Now, if you have MJPEG, this ARTICLE might, or might not, be of help. Even with the correct MJPEG CODEC installed, the limitation with MPEG might eliminate editing MJPEG too.
Good luck, and remember to fully test CS5, Adobe offers a full, 30-day money-back guarantee. Once you buy it, if you do not like it, just return it within 30 days, and you get your $ back.