Tried many MKV files on my Samsung D series TV. It is able see them alll and to play them but "<<" & ">>" don't work (says it's unsupported).
it tried with today's CVS version (as of Aug 20).
(resume from bookmarks is okay though)
Is there another server software you can use where it does work? AFAIK, Samsung's DLNA playback only allows you to use the left and right arrow keys to FF/REW. So I think this is just a TV limitation.
I also have a samsung d series tv and I have the same problem, no FF/REW possible. I also tested mediatomb but with mediatomb FF/REW doens't work either. Other than this, everything seems to work great.