Steam has already supported VDPAU for in-home streaming on Linux as the preferred means of GPU-based video acceleration for the NVIDIA Linux graphics driver and the Radeon/Nouveau Gallium3D drivers. Now Valve has implemented Video Acceleration API (VA-API) support to benefit those using Intel HD Graphics on Linux as their open-source driver is the primary user of this video API. Using VA-API in-home streaming requires the Intel VA-API driver 1.3.2 or newer.
Besides the VA-API support, the latest Steam client beta has a number of fixes, more work in the Big Picture mode, and Steam Music Beta and VR improvements. More details on this latest Steam client beta update can be found at SteamCommunity.com.