I have a video file that I have inserted into a presentation.  In an attempt
to constrain the shape of the video, I have a transparent GIF on top of the
video so that the video edge is curved.  I sent the video to the back and
brought the image to the front.  It looks fine in the preview and when the
slide loads.  However, once the video starts to play, it jumps out to the
front and breaks out of the constraint that the GIF places on it.  Is there a
way to lock the video down so that it stays under the GIF?  Or is there a
better way to add a custom shape to the video file?