first of all, from a branding perspective, the profile picture and banner mesh well together. the thumbnails, however, leave a lot to be desired. pick a colour scheme, font or style for them and design them as such. i've no idea what gamers would want in terms of content, so i'll leave that part out. in terms of your content currently, you sound very close to the microphone, like someone has attached it to your cheek. having that in my ear isn't the most pleasant experience. you also seem a little low energy, which would be fine if your type of video allowed it (such as a vlog, cooking video etc) but with a gaming video where you are the aspect of the video that is added on over the main content, it's a little disheartening.
on the pokemon colosseum episode 7 video, i was very confused with what was happening in the start. it'd be nice for a series to start with your intro, followed by what you did in the last episode, perhaps with flashbacks in editing, and then a starting of the movement in the game. being thrown right into the action was a bit disorientating to a non-gamer. your title could also use a little work. a better format would be; "SHADOW POKEMON?? - Pokemon Colosseum: The Cave of Kids: Episode 7" to entice the viewer to watch, rather than giving no indication what happens within the video. when advertising a tv show, they don't just have it as "tv show name #3", they have a brief description along with it. give someone who hasn't watched before a reason to view.
maybe a webcam could be added, also? it'd be nice to see your facial expressions whilst you're playing the game. furthermore, focus on your diction on certain words - some bits were a little hard to understand.