I still cannot get VDPAU accelerated flash video with adobe flash player 10.2 r154: even though my mplayer accelerates H.264 video perfectly (I have 8800GT GPU).
I do have /etc/adobe/mms.cfg file which contains:
strace shows that Firefox(adobe player) opens this file:
22554 open("/etc/adobe/mms.cfg", O_RDONLY|O_LARGEFILE) = 71
but libvdpau.so is never loaded.
P.S. It turns out adobe flash player 10.2 r154 has some bug which prevents VPDAU from working either in Google Chrome or Mozilla Firefox. Sigh.