Adding Ease-In and Ease-Out to a Video Clip Animation

By default, when you animate a video clip, it will move from its position in one keyframe to its position in the next keyframe by progressing towards it at a constant pace, then stop moving abruptly. If you want it to speed up as it starts moving and to slow down before it stops, you can do this by adding ease-in and ease-out to its animation. Adding ease-in to an animation will make it start slowly and gain in speed as it goes. Adding ease-out to an animation will make it slow down before it stops.

You can set the ease-in and ease-out for an animation in the Tool Properties view.