Youtube videos don't stop if in full screen and Champ select starts [CLIENT]

If I start playing one of the youtube videos on the home-page of the client (For example the recent teamfight breakdown video), queue up for a game, full screen the video, accept queue if it pops, click back to video, champion select starts and I can still hear the video playing in the background. There is no way to stop the video from playing in the background.