It enables you to speed up or slow down the video playback rate with. Just click and hold on the play-pause button for about 5 seconds to access the rate change menu. Interested in learning how to change the speed of a video? Whether you are looking to speed up a travel vlog so it can look like a time-lapse or planning to create an impactful slow-motion effect in your home video, we have the tutorial for you! Quicktime Player For Mac Adjust Player Speed Slow Windows 10.Quicktime Player For Mac Adjust Player Speed Slow Windows 7.