You might want to try Clickwebinar for webinars. I have used their service seamlessly for a couple of months on MacOS and they do the recordings. They are not good though if you need to constantly interact with the audience because the delay in speech through their server is too high (or at least...
I remember that Adobe Media Encoder used to have options for water marking. Check that and possibly, but unlikely Apple Compressor out. Hope that helps!
Teamviewer works across both platforms and is very simple and secure to setup and use.
I am a Camtasia lover for years. Even on a Mac. My internet marketing friends all prefer it except for the few who like ScreenFlow.