That is a pretty nice swing. Where does your hip hurt? I don't see anything in the swing that looks like it may affect the hip. If you could post a face on shot, that would help.
I have been doing a stretching routine for a while from the book below. It has really helped my hip flexibility. I race bicycles for years and my hip flexors and joints got very tight. The stretching section is the best part of the book.
Roger Fredericks Secrets of Golf Instruction & Flexibility: Your Guide to Mastering Golf s True Fundamentals
Another great book or DVD for golf related flexibility is below. Joey D has a few hip exercises in there two. I do these 3 times a week and the stretching above every day. It has really helped my hip flexibility and strength.
Fix Your Body, Fix Your Swing: The Revolutionary Biomechanics Workout Program Used by Tour Pros
Thanks for posting the video.