If it is suitable for you it is better to have yourself on the video. I heard some stories that videos were pirated and reuploaded to the different sites. If you are in the picture it is easier to protect your work.
Hi, you can report those links where the videos have been pirated to Udemy.
Here's the Udemy's trust and safety link:
I do almost all of my courses as voice over. So I think it's fine.