Comment 9 for bug 1395070

you can also try http://media02.nfl.info/NFL/Media/2014/Video15/Officiating_Media_Video_12-05-14.mp4 if that works better -- not sure why it would say file is corrupt, as you saw with chrome it clearly isn't...

here are related packages i have installed when it crashes:

libvdpau1:amd64 0.7-2
vdpau-va-driver:amd64 0.7.4-3
libva-drm1:amd64 1.3.1-3
libva-glx1:amd64 1.3.1-3
libva-wayland1:amd64 1.3.1-3
libva-x11-1:amd64 1.3.1-3
libva1:amd64 1.3.1-3
libgstreamer-vaapi1.0-0:amd64 0.5.9-2
gstreamer1.0-vaapi:amd64 0.5.9-2
firefox 34.0+build2-0ubuntu0
nvidia-331-updates 331.89-0ubuntu5
nvidia-331-updates-uvm 331.89-0ubuntu5
nvidia-cg-toolkit 3.1.0013-1
 nvidia-libopencl1-331-updates 331.89-0ubuntu5
nvidia-opencl-icd-331-updates 331.89-0ubuntu5
nvidia-settings 331.20-0ubuntu8

removal of gstreamer1.0-vaapi also removes libgstreamer-vaapi1.0-0 and libva-glx1, after which firefox is able to successfully play and seek within the video without crashing.