To cut to the chase, over on Adobe Labs is the Adobe Flash Player 11 Beta 1 (v18.104.22.168) where the 32-bit and 64-bit plug-ins can be obtained. Up until now, 64-bit users have been stuck with an outdated Flash "Square" Beta.
In poking around the libflashplayer.so binary from this first Flash Player 11 Beta, it doesn't appear that it yet supports the VA-API acceleration interface available to the open-source Intel driver and AMD Catalyst users, among other drivers/hardware. Nor does it support XvBA. It appears that for hardware-assisted video playback that, for the moment at least, it's still bound to NVIDIA VDPAU under Linux.
But one new addition to Flash Player 11 for Linux does appear to be Broadcom Crystal HD support, which was available in previous Flash Player 10 versions to Windows users. In today's Linux binary are libcrystalhd.so and Broadcom,H264, references.