If you don’t want to spend any more:

• VirtualBox

• OBS

VirtualBox to get around DRM (recording software can be seen if video used in host system) and OBS will allow you to record a window.

If mkv is too large then you can use Handbrake to convert it to MP4 or m4v.

Just be sure to have any mics muted during recording and also mute notifications

I don’t know if they implemented something against screen recording, but I use SimpleScreenRecorder. But even VLC can do screen recording using the “Stream” option.