A role for objects to draw on top of a video. Requires a
process_video_overlay() method, which will be passed the
UAV::Pilot::SDL::Window object that the video is drawing to.
$video is an
UAV::Pilot::SDL::Video object, you can set an
$overlay object with:
$video->register_video_overlay( $overlay );
NOTE: This is still experimental. Lines tend to flicker and show up as black. This is probably due to the SDL YUV hardware overlay.