"Be sure to watch a video without ads" - well I'd love to but I did not find the "watch without ads" button in the Youtube UI. As long as all the videos I come

"Be sure to watch a video without ads" - well I'd love to but I did not find the "watch without ads" button in the Youtube UI. As long as all the videos I come across still ask me to install Flash although I have activated the html5 thing, I fail to see the point...