This is probably why the only answer to the conversion question above used an online service. A lot of people use VLC to capture frames and imagemagick to collect them back together into an animated gif. There don't seem to be that many apps that do the movie -> gif conversion on OS X, though. Look at these two questions for possible solutions:
A video screen capture tool, and a movie to gif conversion tool. If you need to capture video and convert it to GIF, or a very long involved sequence of steps, then you'll need to combine two separate programs.
