Get an nVidia graphics card that's 650 or higher and use ShadowPlay. Writes all video events to two streams: the first is what you see on your screen, the second gets written to temporary memory chip on the graphics card that stores the last 20 minutes of whatever happened on your screen. This way, if you forget to hit "Record" you still have the fight! Also, they've made a lot of enhancements for it so you can record only certain windows and such as well (for fullscreen games). You can also live stream to Twitch if you want to! I've used it a bunch for SWTOR. I'd post up some samples but they're all pretty large files.