Read the statement by Michael Teeuw here.
Rotate the Screencast
Re: Screencast with mobile for MagicMirror
Hello, the installation/presentation for YouTube on the MagicMirror is working well. The only thing is: how can I turn it for 90 degrees to the right, because I’m also using that for my MagicMirror2? And is it already possible to use it for other things than only YouTube?