Ask TWIL: How to Make a Screencast on Ubuntu / Linux
This works for Linux Mint too
There is now maybe easier way to do screencasts and videos
OBS
Open Broadcaster Software
https://obsproject.com/fi?fbclid=IwAR38aJ3LZNDwquAallyJ7e0mxMUKY7YRiJgxpfSOvXfhyZ0rUnonh35J7nY