Opacity over time
I knew how to change the opacity of a video clip but I wanted to change the opacity over time. In order to do this you need to create multiple keyframes. First, click on the clip you want to edit to have in the timeline window. Under Effect Controls>>click opacity. Click to ensure the ‘stopwatch’ button is clicked to the word opacity. Move the current-time indicator to the start of the clip and create a keyframe (click the diamond-shaped Add/Remove Keyframe button). Set the opacity to the level you want to the clip to start at. Move the current-time indicator to the point where you want to make the next opacity setting. Create another keyframe and set the opacity. Keep repeating this process until you have created all the necessary keyframes and settings.