Hello. This question is quite easy to answer, because Files Gallery will support any video that the browser supports. It's not possible for Files Gallery to play videos that are NOT supported by the browser, because it's the browser that plays the video. The recommended solution would be to target
H.265 codec, as this is pretty much universally supported across all browsers.
MOV is an Apple format, normally supported by Safari browsers. However, if encoded with
H.265, it will probably work in other browsers also, but then you might as well name it
.mp4. Original MOV files are mostly unsupported in most browsers.
You can find other video formats and what browsers support them in the links below.
As you will find, unless your videos are already in a web-friendly format (like
mp4), you will likely need to encode them if you want support across all browsers and platforms.