THE PLT WAS PERFORMING AEROBATICS WHILE BEING PHOTOGRAPHED FOR A PROMOTIONAL VIDEO. ON THE LAST PASS OVER THE ARPT THE ACFT LOST AIRSPEED AND BEGAN A SIDE SLIP WITH THE LEFT WING DOWN. AT A VERY LOW ALT AGL THE ACFT APPEARED TO STALL AND ASSUME A HIGHER SINK RATE, STRIKING THE GROUND WITH THE LEFT WING & NOSE. THE PLTS HEAD HIT THE INSTRUMENT PANEL DURING THE CRASH SEQUENCE AND HE LOST CONSCIOUSNESS. THE PLT DID NOT REGAIN CONSCIOUSNESS AND EXPIRED ON 1/3/86. TWO OF THE PLTS FRIENDS, WHO WERE ALSO AEROBATIC PLTS, REVIEWED THE VIDEO TAPES AND CONCLUDED THAT THE PLT MAY HAVE HAD A MEDICAL IMPAIRMENT AND WAS TRYING TO LAND WITHOUT TOTAL CONTROL. NO MECHANICAL DISCREPANCIES WERE FOUND AND THE PLTS LAST MEDICAL EXAM ON 10/10/85 REVEALED NO ABNOMALITIES. THE VIDEO CAMERAMAN, WHO HAD MADE OTHER VIDEOS WITH THE PLT, SAID THAT THE PLT APPEARED UNSUALLY NERVOUS BEFORE THE FLT, HE ALSO SAID THAT THE LAST APPROACH TO THE FIELD WAS NOT A NORMAL ONE.