has a video about . My back starts hurting just looking at that video. The kid should use his legs more, should not bow his back so much, and should not rely on gravity and momentum to lift the weight. If he does that often, he is going to seriously hurt himself. Since that weight is probably more than he could properly lift in the first place, he should wear a lifting belt to help support his back in the attempt.
Remember: If you are unsure how to perform a particular exercise, then you should always seek the instruction of a professional. Most gyms have employees that would be more than happy to help show somebody proper form in a particular exercise.