I don't believe there is any way to directly convert a demo into a easily playable video format. You have to go through with some sort of screen recorder and recapture the video to export it.
try renaming the file as a .avi using WinRar, make sure you have a copy of the file you do it too, incase it doesnt work lol but that usually works for me.
try renaming the file as a .avi using WinRar, make sure you have a copy of the file you do it too, incase it doesnt work lol but that usually works for me.