#1. Captain 8-bit
I "stumbled upon" this channel by using Stumbleupon (see what I did there). There main video series is called "The Game Chasers". This series follows two guys (Billy and Jay) and they go around to different flea markets, thrifts stores, pawn shops, and retro game stores trying to find games for good prices. If you are interested in buying old games this is a good series to watch. I get really jealous when I see some deals they make. They also have a series called "That's the Way Game Playin' Go". In this series they look at memories from their childhood based on a specific category such as Zelda or a console like the NES.
#2. DYKGaming
If you are interested in random trivia about gaming, then this channel is for you. Their videos are short 3-5 minute videos that cover interesting trivia from all of your favorite video game franchises. They have videos on Mario, Final Fantasy, Portal, and other popular video games. They also have another series called Easter Egg Hunting where they play through a game trying to find all the Easter eggs or they find as many Easter eggs as they can that pertain to a certain topic like South Park.
This is one of the most interesting channels I have ever came across. This guy, Matthew Patrick, looks at all of your favorite video games and tries to research real world qualities about them. Have you ever wanted to know what type of frog Frogger is? How about diagnosing all of Batman's villians? They also figure out exactly where Adventure Island is located. This guy puts a lot of research into his videos and they are all very interesting. The video I am including is my favorite one so far. He determines that (spoiler alert if you have lived under a rock) maybe Sephiroth wasn't the one that killed Aerith.