The low-end A10/A13 ARM SoCs has a video decode engine that's now been reverse-engineered for allowing open-source video acceleration support. Proof-of-concept code has been written that shows hardware-based JPEG, MPEG12, and H.264 video decoding for Allwinner hardware. The support isn't yet ready for end-users, but much progress is being made.
The video decode support they are working on is being exposed to user-space via the popular VDPAU video acceleration API. The experimental VDPAU SunXI code can be found in this GitHub repository.
More details on the video decode support for Allwinner can be found via this Wiki page. Embedded below is a video showing open-source hardware-based video decoding on the Allwinner A10 SoC.