johhnedo,
I agree with you, the yaw started about 3 seconds prior to the horn. The real question then is what was he asking of the machine? With his entry into a high OGE hover, with wind, he might very well have exceeded the flight envelope by quite a bit. There also seems to be some incipient VRS, or at least a falling through with too little power for OGE. Not a classic LTE, in any case.
Thanks!