Well, I've watched a lot of gameplay vids and the biggest thing I can suggest is try to avoid "the fanboy zone." What you did is fine but we all know it's easy to favor one thing over another and we all know that not everyone can afford all consoles out there but I really get annoyed when I watch something and it lapses into fanboyism. Plus you risk alienating potential viewers. Doesn't seem like you would do this but it's always something to keep in mind. Best not the feed the trolls you know.
Try to avoid going "um" and "uh." If the gameplay footage is pre recorded ad it's not live, try to rehearse what you're going to say ahead of time and try to avoid any dead air unless there's a cutscene or important dialogue going on. I know this can't apply to live commentary.