Don't remember seeing the video that you are talking about. However I have witnessed two other fatal aircraft crashes and they do make a loud thud. Not as loud as you might have exspected.

You should consider the distance from the crash, the background noise, the voice over sound track and noise being made by the witnesses. The videos all seem to have been filmed more than a mile away. Sound travels about 1000 feet per second ao it would take almost 5 seconds to reach the camera.