Clearly not, since a Pegasos2 G4 can't do it already, while it still performs *much* better than a SAM.
On a SAM, with OS4 MPlayer port (DVPlayer is excluded since it's even slower), you can't expect to read at full speed something heavier than a 360/400p H264.
And regarding altivec, globally (total time spent in decoding + displaying), it brings a 20-30% speedup for H264.
