the new GPU tweek is good aswell and you can record video aswell as tweek in game and overclock while playing.
but FRAPS is the most common and easiers to use just remember when recording the video size for a 1 min video is about 1gb with fraps
But don't forget you can change video capture setting to "half size" which will reduce the file size. After that encode it using h.264 and mp3. The file size won't be dramatic if you edit and encode your videos correctly.