I've found asciinema pretty cool and recorded a few recordings of things I've done, like some experimental Emacs commands, a computer algebra system, a Unicode Tetris game in ARM assembly, and a minimal roguelike: https://asciinema.org/~kragen. These are not the most spectacular recordings on the site, but I have found them a useful way to communicate ideas.

I wish there was some kind of voiceover support.

One thing to be aware of before you try it is that, if you make a recording without providing a filename for it, it uploads it by default to the web site, even if you haven't created an account yet, though it doesn't make it public. So maybe don't record anything you have a responsibility of confidentiality for, or patch out that feature.