How can I change the length an effect will last within one clip. If you don't get what I mean, how can I make an effect like say mirror last for only part of a clip instead of through the whole clip?

You may have to split the clip with the razor tool into multiple sections and apply the effect just to the desired strips.

Toby

Seems like a useful feature to add. I would love it if they would make the transitions similar to the effects where you can choose the spot and length.