It looks that the 32 bit version can use vdpau, a very simple check:
strings libflashplayer.so |grep libv
Just to clarify things: The 32 bit version has VDPAU support, the 64 bit version doesn't have that (yet). Check the binaries.
Next accelleration mode:
strings libflashplayer.so |grep crystalhd
That's even found in 64 bit 10.3.
Kano, it still boggles my mind why CrystalHD doesn't use one of the common APIs (VDPAU or VA-API).
No idea, but xbmc has got native support for it, but i don't have got test hardware. I think the wetab has it in the hd variant.