I witnessed an almost identical situation in the 1970s when I was a crime reporter. In that case the suspect was armed with a handgun and had abducted the female hostage during a convenience store robbery and wound up driving in her car to a park near a local lake, with ultimately a half dozen police cars in slow pursuit. Once there he pulled her out of the car and held her close with the gun to her head shouting various threats. The police deployed in a semi-circle, most in prone positions, about 25 feet away.
I was lying between a patrolman with a .44 carbine and a detective with a 30 caliber carbine. After some exchanges of "put the gun down" the woman managed to break free and dove to the ground about 8 feet from the suspect. In response to shouted commands to "drop it" he raised the pistol in our direction. The two carbines fired almost simultaneously, followed within a second or so by at least one 12 ga shotgun and several .357 revolvers. Of course the suspect, struck by a dozen or so rounds, dropped and died within minutes, The hostage was unhurt.
The outcome can I think be credited to good trigger discipline and to the judicious use of more accurate long guns. I also believe there is a case to be made that the near universal use of high-capacity semi-automatic pistols in law enforcement today has resulted in more rounds being fired in encounters and less accuracy.
Having said all that, and having been present on a number of occasions when police officers fired their weapons (and many more when they aimed them without firing) I am always loathe to second guess the split second adrenaline fueled reactions of cops in the field. The fact is it is very very rare for a hostage to be hurt or killed in such situations. In the video case it was obvious that the officers on scene had to act RIGHT NOW, with no time to deploy a tactical team, snipers, negotiators, etc. The bottom line is that no training can truly prepare someone for such a scenario.