[aquark]

If the teacher is moderately technical then they can gain a lot of flexibility by using OBS (https://obsproject.com/) and its 'virtual camera' feature as your 'webcam' feeding into Zoom.

Then anything you do in OBS is feed into Zoom as a direct video feed and saves Zoom screen scraping and re-encoding the video. You can use OBS's screen capture or better yet pre-download the files and just play them back.