Many people seem to think that YouTube is a good free service to permanently store their videos. Small PSA: Don't!
YouTube has no backup system for your videos. If you, for instance, delete one of your videos from YouTube, then it's permanently gone. If you don't have a copy of it somewhere else, you will have lost it forever.
Why is this important? There have been several cases of people having their YouTube account hacked, and all of their videos deleted. Hundreds of them. *Poof* Gone forever. Permanently out of existence. No possibility of retrieval.
It is understandable that not many people have enormous amounts of disk space, especially if they are prolific with their video creation (or they make really long videos). But do not consider YouTube a safe storage space for them, especially if the videos are important, or your livelihood depends on them. (After all, many people get income from YouTube ad revenue. Some people even make a living on it.) They could be all gone at any moment, in the blink of an eye.