(this post rated G – for Geeky readers only)
Our portable entertainment system is working well so far! The kids are watching a movie on the ipad, with good sound from the Jambox (via bluetooth). The movie file itself is located on a USB drive connected to the macbook in the next room. The movie is streamed to the ipad via wifi and converted to the appropriate format in real-time, using a nifty app called Air Video. At the same time Dave is playing minecraft on the macbook.
Why the jambox? Because the ipad has too weak sound for groups of people watching a movie.
Why store movies on a separate USB disk, instead of on the ipad or mac? Because the ipad has too little space. I could have used the mac, but I needed a separate disk anyway (for backing upp photos), so I put all the movies there because it fits so much more (1.5 Tb).
The nice thing about this setup is that all media (photos, movies, music) is accessible on all gadgets (iphones/ipad/mac). No need to keep track of which files are on which gadget. And simple enough that the kids can play stuff without my help.