If you are curious about the javascript, here is a link to another post that has it. For me, I put the url as the p1 parameter and ‘1’ as the p2 parameter. You may want to use ‘0’ instead. Might be overkill for your needs if a template column works well for you. The main advantage to the javascript is that it will also create thumbnails for videos hosted elsewhere, including videos hosted on Glide.
I believe that second p2 parameter has two uses. For youtube videos, it determines which image to grab. For videos hosted elsewhere, it will grab a thumbnail that many seconds into the video. That’s why I use a ‘1’, because I want a thumbnail at the 1 second mark.