https://bugs.freedesktop.org/show_bug.cgi?id=88152
--- Comment #32 from Michel Dänzer michel@daenzer.net --- (In reply to Arthur Marsh from comment #31)
Failed to open VDPAU backend libvdpau_nvidia.so: cannot open shared object file: No such file or directory [vo/vdpau] Error when calling vdp_device_create_x11: 1 Error opening/initializing the selected video_out (-vo) device. Video: no video
Ironically I was getting that message, even though I've only had Radeon hardware in this machine.
I guess the Xorg radeon driver couldn't initialize hardware acceleration, so it didn't advertise the VDPAU driver name, and libvdpau fell back to its hardcoded default 'nvidia'.
As for the hangs, I suspect they just happen randomly regardless of kernel version. Attaching even more dmesg files just clutters up this report and makes it harder for anyone to make sense of it.