Don't want to be too harsh here, but this video only prove that some guy's should never, ever attempt serious DL'ing. Actually this was bad form SLDL'ing.
Other than getting a qualified coach: Please keep the back flat, shoulders back and get down lower, pushing with the legs. Dl's are really not a pulling movement, it's a pushing movement from the feet up. Suggest a trap/shrug bar rather than a BB. Or only do rack/stand DL's from a bit below knee level, because regular DL'ing is just not for you. Actually you might be better off doing cleans or Hi-pulls for upper body mass.
If you do rupture a disc, pull a ligament, etc, please do it this year,and have the treatments, before ObamaCare kicks in next year.