any one konws weight light object concept?

Question

Hi: I am trying to draw graphics on media player,It works. but when I play a movie, the draw the graphics has been hidden on the movie. and i can not draw on the media player anymore, but if i draw on the brink, still can see some line of graphics. It is said that bcs media player is Weight object, they always hides light object. any body know these concept? How can i do if i want to draw on the movie. is there any setting i need to do or whatever.... pls help. thanks a lot