Real Player with Mac

I have a friend that has mac and is unable to see streaming video on Real Player(audio is fine). Also, she says that there is no icon (in lower right corner) to switch to "Theater mode". Since I don't have a mac I can't tell her what to do.
I know this isn't one of these, saving the world questions, but you'd be doing me a huge favor if any one could help me.
Thanks
MJ