If it has a repo it could be easily installed via a meta package or a GUI element. Integration of 'apt' and the Steam Store would be cool.

I may be incorrect but I believe most codec patents revolve around the hardware implementations which would be covered through the hardware acceleration components that exist in most modern CPU/GPUs.

For video they can just offload decoding of common formats to the GPU, which most likely already has a decoder license. They should also be able to send raw DTS and AC3 over Toslink, S/PDIF, or HDMI.