I could list a bunch of general YTers that cover retro games among other gaming topics, but for those who mainly cover retro games I like Big Ole Words, Hungry Goriya, and Video Works.
If he hasn't already been mentioned, Modern Vintage Gamer (MVG) on the tubes is awesome. He sometimes adds developer insight into his videos and digs beneath the surface of the tech he's talking about.
He's good, but lately some of his videos don't add much considering their lenght. His best type of video is when he dissects the discovery process of console's vulnerabilities to enable jailbreaks.
Some of them you can tell he's stretching it out to hit the magic 10-minute mark. I usually can tell which ones are gonna be interesting by the thumbnail/topic and stick to the cream of the crop.