Here are three guys who talk about gaming on Youtube. They are pretty cool and have some pretty interesting stuff to talk about for the most part.
First up is 'Esper'. He is big into 4th edition and has some videos about why 4th is better than other versions. No matter how you feel about 4th though he has some really cool content in his videos. I particularly enjoyed the 15 video solo quest he plays out on camera - "The Isle of Horns", he used commenter feed back between videos to make many important decisions. The accents make me cringe sometimes but i can't fault him for lack of trying.
Ok, second I want to give some props to Captain Machine. He does mostly reviews but I find him pretty informative and just generally pleasant to listen to. He talks about games I have never heard of and that's cool.
And finally here is Sean Connors from "The Outsiders" channel. Sean posts a lot of DM's tips videos and reviews and stuff. Some stuff is more useful than other stuff but he is very encouraging to new DMs and has some cool ideas. The sound is wayyy to quiet in all his videos so you might have to crank the volume.