Lol and don't even get me started on a 15 month old that's 4.5' long eating XL rats isn't the perfect example of power feeding.And after relooking at your video, that rat doesn't look like a XL to me, looks more like a large rat which is still too much. An XL rat is almost a foot long and about 300-350g. Larges are about 8" and 250g.
And overfeeding doesn't only mean feeding it lots of food, it also means feeding it the largest food it can take as often as it will take it which is pretty much your case.