Using YouTube in the classroom can be like walking on thin ice. One never knows when the ice will give way. I do not allow my students to explore YouTube on their own. Just to much crap.
Regardless, there are some helpful videos available. Here a few sites that my elementary Ss have enjoyed. Keep in mind that I am teaching in an American environment...However, there are YouTube videos suitable for almost everyone, just takes some searching.
Since America just had an election, I thought a look at all the presidents was in order.
Making English grammar more enjoyable.
We have been looking at China.
This video from Thailand my students enjoyed.
We studied the Vikings earlier this year.
These are but a few examples of using YouTube in the classroom! Just have to use some effort before class time and common sense.