Avoid camstudio. Its buggy, slow, all videos are choppy, and the output file is usually a whopping 200MB Per Minute.

Either you used a really old version or you don't know how to save a video
correctly, because Camtasia Studio is a very nice program. I have made
some very high-quality 1920x1080p videos using it. Been using it for years.

Now, my BF1942 videos come out low quality because the game is only
displayed in 800x600 resolution due to its old age. But that's a resizing issue.

I've never seen any free screen recording programs worth keeping. But that's
simply because I never found one I liked, perhaps there's one out there.

You can try HyperCam but it's kind of a cheesy program.

This tutorial was recorded with and edited in Camtasia Studio, and
this game video was edited using the same program.

Edit: It have to be free