OBS - Open Broadcaster Service
It's obviously free, you could also check the website... Anyways, it does require a tiny amount of setup so youtube tutorials are probbaly good idea
Just downloaded it. Was very easy to setup, no tutorials needed. I have it set to display capture instead of application capture, but I'll likely switch to that. If I somehow forget, I can always just crop to the application window in post editing.
I also found a bug with OBS. Apparently if you hide OBS from capture, the Stop Recording button will bug out and only capture 1 to 5 seconds of video, even though I was recording for like 40 seconds. unchecking "hide OBS from capture" fixed that issue.