I cannot reproduce the bug on Ubuntu 18.04 (parole 1.0.1-0ubuntu1, gstreamer1.0-vaapi 1.14.1-1~ubuntu18.04.1).
A system with native vaapi (intel driver) appears to use it, one with vdpau (radeon driver) does not use acceleration at all despite vdpau-va-driver being installed.
I cannot reproduce the bug on Ubuntu 18.04 (parole 1.0.1-0ubuntu1, gstreamer1.0-vaapi 1.14.1- 1~ubuntu18. 04.1).
A system with native vaapi (intel driver) appears to use it, one with vdpau (radeon driver) does not use acceleration at all despite vdpau-va-driver being installed.