OK, watched the video.
Her main complaint seemed to be pain that can arise from the (muscles along the) spine (and of course, that includes the neck) being out of wack/alignment. For a young fit person like her, the out of alignment part is usually due to muscle imbalance that can move a spinal segment what the chiros call 'subluxing' (sp?) which in turn can kind of impinge on a nerve for 'pins and needles' sensations of arms falling asleep.
Her main complaint IS NOT TMJ pain, it's just a 'toss in' and seems to be related most likely to some minor imbalance to the cervical spine and soft tissue attachments.
Basically, he's just doing what chiropracters do; crack the back and neck and other stuff to release tension of muscles pulling spine out of wack. THAT'S what they do.