Probably you have already spend multiple hours watching videos on YouTube. But do you know how this internet service actually works? Do you know for example that the little spinning wheel at the beginning of every video is a small gif picture that on the background is trying to figure out connection speeds and best server-client transmission methodology? This video will explain a lot to you and probably it will give you a few a-ha moments. By the way, have a look at the Computerphile channel. Lots of amazing videos on IT technology like this one.
How YouTube Works