You can change the playback speed of a movie by doing the following

  1. Open the Movie menu
  2. Go to Playback Speed
  3. Select one of the following options: x4, x2, x1.5, x1/2 and x1/4. 

Changing playback speed does not make any permanent changes to your movie so will not be applied to exported files.

To permanently change the speed of a movie, FlashBack Pro is required and can be done by doing the following:

  1. Select the frames that you want to speed up or slow down
  2. Open the Actions menu
  3. Go to Movie Speed
  4. Select whether you want to speed or slow down the selected frames