The youtube video below explains the Windows Task Manager, how it works and how to use it.
IMPORTANT NOTE: It doesn't matter what type of computer, tablet, smartphone you use. YouTube works in the similar way across ALL operating systems.
YouTube & Advertising
This is a Google owned business and they make their money through advertising. When some videos start to play there may be an advert appearing. Usually (not always) there is an option to click the advert off after around five seconds. Once this option is clicked the video you want to watch will continue to play.
The video explains how the Task Manager for Windows 7, 8 and 10 works.