First, sorry for my english.

I would like to watch MRVB movie files on BeOS/Haiku. What about codecs for this format? Is there any way to use linux or windows codecs?

I’m guessing you man RMVB, these are RealMedia formats, whcih are closely guarded proprietary formats with no open-source support. Theres no way to play them on BeOS and theres not likely to be for some time.

The Helix Player (an attempt by RealNetworks to go partially Open Source) may help you… if you manage to compile it under BeOS!
Looks like nobody ever tried to port it to BeOS, but that’s something that could defenitively be done. I may have a look at its source code whenever I have some time to do it… (not in the coming days though…).

The Helix player port is currently a dead BeUnited project. I don’t know much about Helix, but I wonder if we could just utilize their codecs to create our own Media Kit addons.