Hello All,
I'm running Fedora 23 64bit, I've been searching online for a solution the last couple of days but without success.

The screen blinks constantly when doing streaming with hardware decoding enabled.
I have a Nvidia GT 730 (has vdpau support) with proprietary drivers with the 32bit compatibility libraries installed.

I run Steam with
LIBGL_DEBUG=verbose steam

At first it was complaining it didn't find /usr/lib/i386-linux-gnu/dri/nvidia_drv_video.so
I saw nvidia_drv_video.so on /usr/lib64/dri was actually a softlink to vdpau_drv_video.so
So I installed libva-vdpau-driver.i686 and created a link pointing to the 32 version.
Now /usr/lib/i386-linux-gnu/dri/nvidia_drv_video.so points to /usr/lib/dri/vdpau_drv_video.so
(I also tried linking to lib64, but it will complain about not being 32bit)

Now it finds the driver, but somehow complains it doesn't have a required function.
libva error: /usr/lib/i386-linux-gnu/dri/nvidia_drv_video.so has no function __vaDriverInit_0_32

If I look at the 64 bit version running vainfo I get:

libva info: VA-API version 0.38.1
libva info: va_getDriverName() returns 0
libva info: Trying to open /usr/lib64/dri/nvidia_drv_video.so
libva info: Found init function __vaDriverInit_0_38
libva info: va_openDriver() returns 0
vainfo: VA-API version: 0.38 (libva 1.6.2)
vainfo: Driver version: Splitted-Desktop Systems VDPAU backend for VA-API - 0.7.4
vainfo: Supported profile and entrypoints
      VAProfileMPEG2Simple            : VAEntrypointVLD
      VAProfileMPE♥♥♥♥in              : VAEntrypointVLD
      VAProfileMPEG4Simple            : VAEntrypointVLD
      VAProfileMPEG4AdvancedSimple    : VAEntrypointVLD
      VAProfileH264Baseline           : VAEntrypointVLD
      VAProfileH264Main               : VAEntrypointVLD
      VAProfileH264High               : VAEntrypointVLD
      VAProfileVC1Simple              : VAEntrypointVLD
      VAProfileVC1Main                : VAEntrypointVLD
      VAProfileVC1Advanced            : VAEntrypointVLD

If I read it correctly, it seems that the init function for the 64 bit version is __vaDriverInit_0_38 but steam is trying to use __vaDriverInit_0_32 for the 32bit version. I don't know if the driver is wrong and doesn't have that function, or if steam should be trying to access it using the 0_38, or if it's a libva or vdpau driver issue.

I see people online who were able to make it work for Intel GPUs, but those solutions didn't work for nvidia.
I also tried exporting VDPAU_DRIVER=nvidia
and following the last part on https://steamcommunity.com/linkfilter/?url=https://wiki.archlinux.org/index.php/Talk:Steam

Finally, I'll leave the log when trying to stream a game:

libva info: VA-API version 0.35.1
libva info: va_getDriverName() returns 0
libva info: Trying to open /usr/lib/i386-linux-gnu/dri/nvidia_drv_video.so
libva error: /usr/lib/i386-linux-gnu/dri/nvidia_drv_video.so has no function __vaDriverInit_0_32
libva info: va_openDriver() returns -1
INFO: CVAAPIAccel: vaInitialize() failed: unknown libva error
INFO: VDPAU hardware decoding
Installing breakpad exception handler for appid(streaming_client)/version(1.0)
INFO: Marking frame 4354 complete with status k_EStreamFrameResultDroppedReset
INFO: Marking frame 4355 complete with status k_EStreamFrameResultDroppedReset
INFO: Marking frame 4356 complete with status k_EStreamFrameResultDroppedReset
INFO: Marking frame 4357 complete with status k_EStreamFrameResultDroppedReset
INFO: Marking frame 4358 complete with status k_EStreamFrameResultDroppedLate
INFO: Timed out waiting for render, resetting decoder
INFO: libav error: decode_slice_header error
INFO: libav error: no frame!
INFO: Marking frame 4362 complete with status k_EStreamFrameResultDroppedDecodeCorrupt
INFO: libav error: decode_slice_header error
INFO: libav error: no frame!
INFO: Marking frame 4363 complete with status k_EStreamFrameResultDroppedDecodeCorrupt
INFO: libav error: decode_slice_header error
INFO: libav error: no frame!
INFO: Marking frame 4364 complete with status k_EStreamFrameResultDroppedDecodeCorrupt
INFO: libav error: decode_slice_header error
INFO: libav error: no frame!
INFO: Marking frame 4365 complete with status k_EStreamFrameResultDroppedDecodeCorrupt
INFO: libav error: decode_slice_header error
INFO: libav error: no frame!
INFO: Marking frame 4366 complete with status k_EStreamFrameResultDroppedDecodeCorrupt
INFO: libav error: decode_slice_header error
INFO: libav error: no frame!
INFO: Marking frame 4367 complete with status k_EStreamFrameResultDroppedDecodeCorrupt
INFO: libav error: decode_slice_header error
INFO: libav error: no frame!
INFO: Marking frame 4368 complete with status k_EStreamFrameResultDroppedDecodeCorrupt

Any help you could provide will be greatly appreciated.

Thanks!