[aiharkness]

My opinion, I suspect the video download on your BlackBerry from your son's BlackBerry was interrupted or somehow failed. Or it failed on your son's end. That's why you see the file name but with a size of 0k, and why it won't play.

I would experiment. Have your son send it again, and watch the download on your BlackBerry after you accept. See what you see. I'm guessing it fails almost right away after you accept. If you get an error message, note it. Also, ask your son what he sees on his end.

I've done this with pictures and music over BBM between me and my wife's BlackBerry. If I ever had a failure it didn't make an impression on me. (But there is a size limit. I have tried to send files that were too large, and gotten an error message accordingly.)