Yeah most recording software doesn't capture the full screen because the recording software is set to record a window. In full screen your screen is white or black, but you see the main game on your end. In windowed mode or borderless window you literally keep the game set to a window (you can't even tell a difference between full screen or borderless window.

Yeah it took many many tries for me too, but once I had it down. Normally I could make it to phase 2 without getting hit. The end varied depending on how I reacted. The time I won I had 60 something hp left for his last move. Ended with 12hp too. Yeah Sans is too awesome to hate. Even after all you did, you just...can't hate him. Reminds me of one ending in the inFamous games (inFamous 2).