Hmm, I am not sure on that one.

Since you are sharing the laptop's internet connection with the PS3, I imagine things work differently than if they were simply two units on the same network.

My buddy uses TVersity for his PS3 to access media files on his computer, but he has it wired directly into a router.

I just keep all my media stored on a five hundred gb external hard drive I have dedicated just for use with my 360. For me this works fantastic, so I have never even bothered figuring out how to stream my stuff through the network.