To record gameplay video, you can use recorders like Camtasia, Jing or Free Online Screen Recorder. I prefer the third one, because it is free and has no recording time limit. This article will tell you how to record game with this recorder. http://www.apowersoft.com/record-gameplay.html
"How many times have you wondered how in the world people put their gameplay footage from Xbox 360 and PS3 on YouTube and have such good quality? One YouTube director is creating a series that is a walkthrough for getting started."