Video file extensions compatible to use in Presenter

What is the proper file extension for videos to be used in Presenter? (mp4, etc.?) Every time I try to import a video file (usually YouTube downloads) I get a message that says that the file is not supported, do I want to convert it? What is it converting it to?

Videos must be in .mp4 format. If you import in a different format, Presenter will ask if you'd like to convert the video file so that it is compatible with Presenter.
https://www.worshiptools.com/en-us/docs/33-import-media