Currently (up to f25) the VAAPI provider for intel DDX is set to va_gl With the modesetting driver it is set back to same as the DRI driver. There is a need to check if other DRI drivers can work with VAAPI under GL (va_gl) and modesetting (specially on others arches). https://bugzilla.redhat.com/show_bug.cgi?id=1392917
This bug appears to have been reported against 'rawhide' during the Fedora 26 development cycle. Changing version to '26'.
I've put this one on my to-do list. I need to think a bit about how to best solve this, but I will try to get this fixed soon.
xorg-x11-server-1.19.3-2.fc26 with a fix for this is now building.
xorg-x11-server-1.19.3-2.fc26 has been submitted as an update to Fedora 26. https://bodhi.fedoraproject.org/updates/FEDORA-2017-ff342c515a
xorg-x11-server-1.19.3-2.fc26 has been pushed to the Fedora 26 testing repository. If problems still persist, please make note of it in this bug report. See https://fedoraproject.org/wiki/QA:Updates_Testing for instructions on how to install test updates. You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2017-ff342c515a
xorg-x11-server-1.19.3-2.fc26 has been pushed to the Fedora 26 stable repository. If problems still persist, please make note of it in this bug report.