Hmmm ... I thought a-GIF playback was a function of machine video speed (?? to some extent). Every frame is displayed in an a-GIF ... as opposed to an AVI where frames are skipped to keep sound and video in sync if the playback is slow. Another drawback to a-GIFs is that they are in only 256 colors. This is not a problem if your intent is posting the a-GIF on the web as a quick preview for others. Image quality can suffer if you use substantially more colors than that (ie lots of gradient changes).