Why it worked
The video likely worked because of the extreme "gross-out" factor of the initial state of the car, combined with the satisfying transformation to a clean state. The "before and after" format is inherently compelling, and the shock value of the mess likely drove engagement.
Summary
The video shows a car interior that is extremely dirty and covered in what appears to be vomit. The cleaning process is then shown, with the car being steam cleaned and scrubbed. Finally, the car is shown to be clean, with a "before" and "after" comparison.