Hello. I have pretty much the same issue. I have just installed PS3 Media Server (latest BETA) and it found my Sony Bravia Networked TV (using Bravia5500 config). I was able to take a VOB file of a DVD and stream it to my TV no problem.
However like you, the Fast Forward and Rewind do not function (pause/play/stop work). Everything else seems great (although chapters don't work either, but from reading other posts briefly, doesn't seem like it's supported?).
Anyway, anyone know if there's a tweak/fix that would allow FF/Rew to work?
Appreciate it and thx for an awesome piece of software!
EDIT: Some more info. When SeekbyTime is set to "true" in the config file, what happens is that when I touch either the ff or rew, nothing happens. However, if I hold down the FF or REW button, I get a little seek window that pops up and the time bar moves forward/backward accordingly. However, as soon as I let go of the button, the video starts over from the beginning. This is with a VOB file. Haven't tried any other video format yet.