I use Shadowplay (Nvidia Specific for GTX650 and up type video cards). You can record as much footage as you want using the Alt+F9 keystroke. The 5-20 minute buffer limitation is for when something cool happens in game and you want to save a snapshot of that event using the Alt+F10 keystroke. To use it, you must install GeForce experience software on your computer (i.e. Free from Nvidia). One thing with shadowplay is that it creates videos with variable framerates. Some playback software doesn’t handle this situation correctly. So after I record my videos I’ve been using a program called Handbrake to then convert the shadowplay videos to constant framerate videos.