I'm clueless when it comes to linux. I did look at direct show and it's only supported through 3rd party wrappers. out of the box, I think the JMF uses it's own rendering engine. I would expect a similar apprach on linux. in my experience, any java api willl share as much as it can between platforms, and only the very lowlevel bits are implemented on a specific platform. this is evident in the comms api.
having looked at this VLC player however, it's great. it has a web interface, a telnet interfce, a command line interface, and a native interface. it works on multiple platforms and it plays just about everything out of the box! I think the choice has been made