Fortunately, the pilot and three passengers were not injured. Also fortunate was the fact that the photographer lived to film another day. According to the photographer's description on YouTube, the aircraft passed less than 10 feed from their position.
The NTSB determined that the probable cause of the accident was the pilot's failure to maintain directional control during takeoff.
Crash During Floatplane Takeoff in Anchorage, AK 7 June 2009
NTSB Factual Summary (PDF)
NTSB Full Narritave
NTSB Probable Cause Determination (PDF)