LoiLo Game Recorder is a completely free, fast, simple and very effective videogame recorder.
It can use either a Windows GUI hook to capture desktop windows, or an OpenGL/DirectX hook to capture most games. Recording is as simple as choosing your game from the list of running applications, alt-tabbing to your game and pressing the Record hotkey. Optionally, you can have it display your framerate using an in-game overlay for performance testing, with or without recording.
The game is captured in full resolution or 360/480/720/1080p and saved using Motion-JPEG with a configurable quality level (5-99%) and any common framerate. The file is compressed less than with most codecs, resulting in larger size but higher performance and excellent image quality (certainly better than most current alternatives). The video can then be converted to more manageable formats such as MP4/H.264/AAC for streaming (recommended: Freemake Video Converter - results in small file with great picture quality in no time at all).
Note: Loiloscope is automatically installed along with this. Loiloscope can simply be uninstalled afterwards, no harm is done.