The Xbox app shipped with Windows 10 can record the active window as a game clip. It requires rather modern graphic cards to work. Nevertheless, it can be a handy option if you run Windows 10 in a modern PC and don’t want to install any extra software.
The VLC media player can record the whole desktop with its Convert tool. You can bring it up by holding the Ctrl key and press r and choose the Capture Device to be Desktop. It should work in all OS that VLC can run.
A dedicated free screen cast and streaming program is the Open Broadcaster Software, known as OBS. It works in all major OS, has intuitive GUI to tune many settings, and won’t slow your computer down.
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