Owl Attacks Heron On Live Cam

I love all the live nest cams that are available for us to watch online but knowing all the things that can go wrong with nesting, I keep waiting for the day when a nest cam witnesses something violent.  Sure, we've had epic peregrine battles, but when we are we going to see something pick off nestlings...we might get that this year with the Cornell Live Heron Cam. Recently, a great horned owl tried to go all Hunger Games on the incubating heron.  Check out the video and the heron gets angry and loud, so keep that in mind if you are watching this at work or if you have headphones on (don't worry, it's not bloody):

http://www.youtube.com/watch?feature=player_embedded&v=RBGYPQKt3wA

The birds have just started incubating, but if that great horned is that brazen now...will it return when the chicks hatch?  I don't think this is a matter of the owl desiring a nest, I've seen great horneds take a nest in a heron rookery--it was interesting to note that the herons didn't take any of the nests next to the owl nest but seemed to get along fine with a red-tailed hawk nesting among them.

Will the herons be able to protect their young from an owl? A few years ago there was a raccoon that was systematically climbing up trees at a heron rookery in MN and eating the young one by one.  The MN DNR got video footage of it and in some cases the parents watched from a nearby branch without attacking the raccoon that was eating the chicks alive.

How will this nest cam end? Happily with all five chicks flying off or brutally with some being eaten by an owl? It certainly has my attention.