Glad to hear you got it working.
For recording games I usually use the Open Broadcasting Software which supports recording as well as streaming. Videos are large and the size depends on the amount of pixels changing (for example a video of a non-changing white wall doesn’t take up as much space as say, an FPS game where things are changing constantly). Don’t get too worried over how much space the video takes up, unless you’re really tight on hard drive space in which case I think you have better things to delete for. 