Steam added an excellent screen capture feature to their overlay, but I like being able to capture my screen anytime, not just when playing games with the steam overlay.
gpu-screen-recorder is the perfect tool for this, you set up a command to run at startup and the software records the last X minutes in the background, with barely any hardware utilization. Add a hotkey for another command that saves the recorded clip to a file, and boom, simple and efficient replay recorder. I'm honestly surprised this app wasn't mentioned yet.