The process of browsing and watching videos on www.YouTube.com

When one watches one video on YouTube then the viewer sees something that catches their eye in the "Related" section on the side and watches this video then finds another interesting video on "Related" and watches and so on. This process can last for hours, leading the view to videos completely unrelated to the original video they watched, this is very important to discovery of small videos. It is sometimes very hard to stop once you've started.

the act of going on to youtube.com to research one video and then the next thing you know you have clicked so many links you have been on for hours

A website that is owned by Google that has absolutely terrible copyright rules, thanks to the DMCA.

when one searches for new youtubers to follow.

A site that was once about, well, you is now about whoever makes the most money.

Are you an animator? YouTube doesn't give two shits and they'll never support you.
Do you want to be a critic? Ha! If you want to get a copyright strike then go for it!
Do you want to express your opinion? Get ready to be hated and get your channel taken down for no reason?
Do you want to do anything creative? Go fuck yourself - YouTube

If you want to be successful, do something easy like becoming a let's player or a vlogger. Oh yeah, and make sure you have a pretty face so idiots can fantasize on being in bed with you.
Or you could become the utter scum of YouTube and become a reactionist. What's a reactionist? They're basically people who watch a video and do nothing but yell, "oh shit" or "dayum!" without being creative. In fact, they steal the video!

So there you have it. A site that can be amazing but chooses to be shit.

Someone who uploads youtube videos, particularly someone who has some what of a fan base. Although it can mean anyone in youtube, it specifically means someone who makes videos.