Well, in the FAQ http://java.sun.com/products/java-media/jmf/reference/faqs/index.html#jmf2-support
is says for supported (video) formats:
video: AVI, MPEG-1, QT, H.261, H.263
Which would do I think for my puroposes.
However it depends on how well it outputs such videos and how easy it is do deploy JFM with your game. The JMF's pure Java probably is more simpler to handle, compared to the native lib needing "Performance Packs".
We'll see. The reason I asked here is to find some potential game dev/user experiences with JFM.
P.S. My first test with the pure Java JFM version doesn't want to show my Mpeg1 video, just sound. Onhttp://java.sun.com/products/java-media/jmf/2.1.1/formats.html
you can read why: the pure Java version doesn't render Mpeg video.