I'm not sure if you realize it but, as long as your logged into your Google account (like I am), anything you watch there is going on your permanent record. There are ways to Delete it, but who has time to dig through all that.
There is a setting in Youtube called autoplay, located just below the video a blue on off slider.
See CNet's article Here
Save yourself the frustration, the wasted bandwidth, and a fun game of "Which tab is playing that $#^% video"
Otherwise you may get an hour and a half of random (picked by youtube), anime video game clips (of a title you've Never heard of).
Change it now or suffer the consequences!