I will explain. 100% of something means all of it. back in his day, there was no youtube (I know it's hard to imagine). if there was no youtube, there were 0 youtube videos. all of these 0 videos contained brainrot, so 100% of the videos. i'll give an example that will make this very understandable. suppose you have 0 cookies and you ate all of them, you ate no cookies. you ate 100% of 0, which equals 0 cookies. i hope your math is mathing again, and that you have more than 0 cookies.