I recently attempted to capture some in-game footage - only to find that the recording was simply way too dark. Way darker than what it had been on my screen. It was fixable in my video editor, but the root cause was not immediately apparent - clearly it could not have been a monitor setting as it would have affected video and game equally.
It turns out that I was running the game - Skyrim - in Fullscreen Windowed mode, so it seems to be using the desktop gamma/brightness settings. Fraps on the other hand uses the ingame brightness settings.
When I changed in my ingame brightness, the picture on my screen remained exactly as it was before, but the brightness of the FRAPS video changed. Very counter-intuitive, but there you go.