If my students want to use a video recorded in HEIF, I have them convert it to the H.264 format. There are a number of free online conversion sites they can use, or they can use the Handbrake app set to use H.264 with a constant frame rate. They can record videos in H.264 on an iPhone with the Most Compatible setting and on an Android phone with the High efficiency video toggle switch in the Video Size setting turned off.