Just got an email from Recorded TV HD. Looks like RecordedTVHD and maybe many other 3rd party plugins for WMC won't work in Windows 8.1 :(
From the RecordedTVHD website.
Recorded TV HD will NOT WORK on Windows 8.1 Media Center
Microsoft has broken integration points for 3rd party plugins with Windows 8.1
Windows 8.1 is about to be released to the general public and I'm sad to say, that at this point, most Windows Media Center 3rd party plugins will not function.
So if you would like to continue using Recorded TV HD, please DO NOT UPGRADE to Windows 8.1.
At this point I have no news as to whether or not Microsoft is going to fix this problem, but I would guess at some point they will... especially since they are charging users to add Media Center to Windows 8.... but I just don't know.
I just thought I would give you all a little heads up before you see the option to update to Windows 8.1. In the future you can check the main page of the forums for updates on compatibility with Windows 8.1.
Thanks again for using Recorded TV HD!