It looks to me like a too-early rotation (lifting the nose off of the runway). This may have happened as a result of a miscalculation of the rotation speed (known as Vr speed). A miscalculation of the Vr speed, for example, can happen if you derive this speed using a lower than actual aircraft takeoff weight in your performance calculation. This would lead to a calculated Vr speed that was less than was required.
If this was the case, as the pilot rotated the aircraft into the liftoff attitude there would not enough speed to allow the aircraft to climb out. Instead the aircraft would stay on the ground (or in ground effect) until it accelerated to the proper lift off speed.
The crew could also have miscalculated the power setting necessary for takeoff by using an incorrect temperature, or physically failing to advance the thrust levers to the correct position. Since the B737 in the video was a later model it likely had a Flight Management System (FMS) that would have calculated the takeoff thrust setting based on keyboard entries made by the crew.
Also, it's common for the takeoff thrust to be set, based on the FMS calculated values, using the auto-throttle function (sometimes takeoff thrust is manually set by the crew using the calculation provided by the FMS[or similar]). In other words, after initially moving the thrust levers forward a bit, the pilot would just push a button on the mode control panel and the throttles would automatically move to the proper takeoff setting. Again, this would depend on the proper information being loaded into the FMS/FMC so that proper calculations for Vr speed, thrust setting, etc. would be utilized.
There are many variables depending on what procedures the crew used and the pilot technique, but the video shows the airplane rotating and not lifting off, and just my opinion, but this was likely because the rotation was started at a lower speed than was appropriate.
Here is a link to a incident involving a B737 that appears to have some similar circumstances.
B737 tail strike