​Movie Overlays work just like Image Overlays, but use a video file instead of an image. This is great for an animated logo or lower third. Movie overlays will play without sound.

Video files with transparency are best. These can be created in apps such as Adobe After Effects, and should be saved as Apple ProRes 4444 format, HVEC with Alpha, or WebM. 

Other video formats may also work. Unfortunately, Apple dropped support for several older video codecs in macOS 10.15 Catalina, including PNG codec.