I am experiencing the same trouble with my i3-4130T CPU and Intel HD 4400.
It works fine with 3.13, but doesn't work on 3.14 and 3.15-rc8 kernels.
The symptoms are the same, I see only a picture or short line of a "video" while the rest is static.
adding Option "AccelMethod" "sna" didn't help me.
Also works fine via OpenGL.
Regards,
Alex