Karel let me know is this works, I have been trying to install mplayer on my 770 as well but I have the same problem. I even have the above repo, but when I tell it to install hildon-fm1 it tells me I need libossomime0 (>= 1.4.17) and I have no clue where to get this install, I tried once and it FUBARed everything (always read apt-get messages before saying yes)