I'm not familiar with much of that, but if you're using PC, there are several screen capturing programs that are cheap and should work well. Check out what Sal from Khan Academy uses--I think it's pretty cheap. There are also some cheap Capture Cards out there, but that would be too much for what you want to do, so I think you should look into screen capturing programs. I think there's some free ones, too. Sorry I don't really know much!
If you're using Windows 10, try the xbox app, which allows use of the "game bar". It has built in screenshot and recording. It also has a feature in which the last 30 seconds are always being recorded, so if something cool happens, you can hit a key stroke and save the last 30 seconds of video.