Here is the full video regarding the fault of disconnecting the bar from the body during the dip and drive of the jerk as I promised last week. When athletes first learn to perform the Jerk, they are cued to go fast. This poses a problem for coaches with athletes who dip so fast they lose contact with the bar. 
I teach my athletes that they do not have to dip quickly. In fact, they should dip slow and controlled. What needs to be fast is not the dip, but the reversal direction into the drive. Losing contact of the bar will only make the bar feel heavier and could cause pain as the body collides with the barbell on the drive up.
One cue I use is; "let the bar take you down" into the dip. Doing so tends to cause better control. When cues fail, I try these drills. They are certainly not the only ones that exist, just the ones I often use.