Haha. In all seriousness, commentary is the most important part, and I really don't think a planned topic is always needed. Jot down a few points you'd like to make about anything, whether it be about the game or something that has happened to you recently, and from there, just kinda let the commentary flow. It's like a conversation with yourself XD Always try to get your viewer base involved in the video, with either a comment saying "I like to use this gun. Let me know your favorite set-up" because using this call-back feature (Like a good priest always knows

) will have them coming back for more because they feel like they are... a part of your video rather than just a spectator.
Hope this helps at all XD If not, pretend that you never ever read this ever o.o not even if there's a fire.