Hey @Jools.
Your deadlift form looks OK, although you sort of seem to be rowing the weight up after you bring it past your knees.
What could be causing your pain might be more to do with a posture issue. This might give you more guidance - http://muscularstrength.com/article/Fix-your-posture-A-simple-yet-complicated-guide-to-spinal-health#
Also, check out this video:
Jordan