It'd be quite handy to have the ability to reverse clips to make smooth gifs without having to export the individual clip from Screenflow, reverse it in iMove, export it out of iMovie, and place it back to Screenflow. This is a pretty heavily requested feature and it'd be nice to see it added :)
Absolutely fill out the feature request form. I think the developers are listening. The more requests the greater it'll impact development priority.
ScreenFlow Feature Request FormReply