A witness reported that he observed the airplane lift off and fly low over the length of the runway several times before it entered the traffic pattern to land. The airplane approached the runway normally, however, it touched down about halfway down the runway at a high rate of speed. Towards the end of the runway, the airplane turned sharply and exited the runway surface. The airplane traversed down an embankment and abruptly came to rest at the bottom, substantially damaging the firewall and right wing. The pilot did not report any anomalies with the airframe or engine.