The stuck box may be a new feature that you didn't know about. It got me too until I watched the video.When you edit someting the autoscroll gets turned off. You need to click in the window to get autoscroll rolling again.
See below for the 64 bit question.
From the celemony FAQ:

Sonar
The current version of the singletrack family (i.e. Melodyne editor, assistant and essential) is tested and supported by us in the following constellations:
OS:
Windows 7/64
Version:
Sonar X2 Producer (64-bit version recommended)
Please note that we do not recommend the 32-bit version of Sonar. Only use the 64-bit version. Please, also use the Melodyne version 2.1 or later in their respective 64-bit VST2 variants.
If your personal Sonar configuration differs from what we have tested, we encourage you to
test Melodyne editor for 30 days free of charge. If Melodyne performs well on your system during the test period, it will still do so after you purchased it.