I have a Tablet PC and am running MS OneNote. I use a webcam to record
videos right in OneNote. If I play the video back on the OneNote page,
where it is stored, it shows up and plays perfectly on the screen of
my TabletPC. The problem is, however, if I try to connect my TabletPC
to the LCD projector that I use, the video part of the OneNote page
shows only as a black screen on the big screen/LCD projector. It does
still show up on my TabletPC's screen. The audio works fine; the video
doesn't work. Also, I can see the video on the big screen if I use
something like MediaPlayer alone; once I use OneNote, however, it
doesn't work.

Do you have your Video output to the LCD projector setup as a separate
display, you cancheck this in the Display Settings icon in Control
Panel.

If you do then I have seen this problem before, I run a dual display
setup and cannot play video at all on the second display i.e. I get
the black box.