The pax video is both fascinating and shocking to watch. It appears to start just as the t/o roll begins and the impact is 27 seconds later, so the a/c must have been almost at rotation - hence the power of the impact. It is remarkable that there was no fire.
The pax holding the video camera must have been badly bruised as he appeared to be sitting forward and turned through 90 degrees to see out of the window. As he landed up on the floor, it's possible that he did not have his seat belt fully fastened, so that he could sit further forward. A very good lesson there for pax who don't listen to the safety briefing.