As it's become too much of a hassle, I need you to start formatting your edits correctly when adding videos. If there isn't a gallery set up yet for a video section you just need to add
where FILE is "File:video name" (without the quotes) otherwise if there is one, you just need to add the "File:video name" into the gallery. I can't keep going back and fixing each one so I will undo the edits unless it sticks to that format, thanks!
So more specifically when it comes to videos in galleries, you have to do "File:X" where X is the name of the file/video (simply putting the file name itself won't make it appear, it's finicky). And yeah, the media thing is... iffy. In this case, it's easier to just add the source text.
Also remember to close the gallery with the </gallery> tag as well.