I'm sorry to confirm that in the 64bit beta1 this does not work on the MD
I had to upgrade the driver manually on the MD and add the changes to /usr/pluto/share/Resolutions.conf on the MD.
I had to rerun the Avwizard.
Now I got the option to select 1366x768, but when selecting it, the resolution was still 640x480 after the change. I went with it and finished the AVWizard, and it rebooted. After booting it started rebuilding the UI. The resolution was only 640x480.
I looked in the /etc/X11/xorg.conf file and there was only a modeline for 640x480, resolution and virtual size was also set to 640x480. TV mode however was set to 1366x768.