Joe Belfiore took to twitter for a few hours today in sort of Reddit AMA fashion, he answered questions about Windows 10 and Windows 10 for Phone from Windows enthusiasts.
Joe B. was asked about when we would get to see a video demo of Windows 10 for phones. As you know it wasn't really demo'ed during last week's Windows 10 event, just the action center, new resizable keyboard and then universal apps were shown off.
During that event Joe B. did say the first build of the new 10 OS would be available after the Super Bowl.
He gave further hint of that today by tweeting that a video demo of the Win10 OS should be available in 1-2weeks from now, that's the week after the Super Bowl...
So it is highly possible that this video will become available once the OS is available, as it made serve as a guide to Windows Insider members who will be downloading the OS on their Windows Phones.