YouTube videos will not play - BlackBerry 8830

[I275fla]

Hi, I just recently reactivated my BlackBerry 8830 not too long ago.  I am running Version 4.5.0.138.

When I try to play a YouTube video the media player pops up and I get this message instead of the video:  "The media being played is of an unsupported format".  It used to work fine a few months ago when I had service; I made sure that I have the most recent BlackBerry software.

By the way, I use the mobile version of YouTube.  Will I need to download an update to my BlackBerry 8830?

Any help would be greatly appreciated - thanks!