I put the video up so she could see how fast and hard they come down... you can hear the bird thump against her head. I don't think any too could stand up to that, especially with a hungry bird or a bird with hungry chicks she needs to feed.
I just want to point out that the woman who got the brunt of the attack from that hawk was wearing a microphone; of course you would hear the thump against her head. Another thing that Jen also pointed out was that the hawk was unintentionally let out in an environment where it was expecting to get fed pretty quickly after being let out. If there is no food, he would be going to look for the food.
My two cents on the topic:
I've heard of (and met) a caique in my area that has been attacked by a hawk and managed to get away with minimal physical damage and survived to tell the tale (so to speak). This caique was not an adult nor was she meant to be out flying; she managed to get out in a freak accident and was missing for about a month. The owner had later spotted her bird being attacked and saw her get away and when she went to look for her bird she had no luck. A week passed and she was assumed to be dead after the attack, but as she was on her way out somewhere, her little baby girl came walking up her porch! She got her to the vet and all was well. Now, do I think there is no risk of a parrot being killed by a hawk? No. There is definitely a risk, but you also have to consider that if you have a free flying bird that has TONS of experience flying, then they at least have a heck of a lot better chance at survival against a hawk than this caique did. You also have to realize that Amigo is bigger than a caique and could do more damage to the hawk. From what Mare has posted about Amigo in this thread, it sounds like Amigo would be fighting the hawk and not sitting there doing nothing. Not saying that for sure that Amigo would win, but he does stand a fighting chance.
I also agree with what Jen (jmfleish) said about the psychological damage that could be done by bringing Amigo inside permanently again. Imagine if you were allowed to do whatever you wanted for the past two years and didn't have to worry about being bored or how to get places or what to eat. Then suddenly, you can't do anything you really want and you are confined to a closet sized space for the rest of your life. You would turn out depressed and angry. Mare did take a risk with Amigo but she also clearly understood the risks, but the positives from letting him fly outside had to outweigh the positives for letting him live indoors only. I don't know Amigo's whole story, but I believe that the choice to have a bird free flying outside is the choice of the owner and the bird and that in most cases, they are doing what is best for them.
Another thing I wanted to mention is that the air changes when a hawk is in the area. Most people don't notice, but if you have worked in an outdoor aviary (or have one of your own with smaller birds), you might notice this. There's an alarm call, then ALL of the smaller birds go silent and tense. It happened one morning at the zoo when I was counting birds, everyone went silent all of the sudden and cleared away from the top of the aviary and I ended up surrounded by quite a few tiels. I looked up a moment later to see a pissed off hawk seriously rattling the aviary cage and trying to break in to get a bird. I'm sure that from living outside for two years and being smart, Amigo has learned the alarm calls of the local birds and seen them all taking off or going into hiding.
One last thing I wanted to point out to those people suggesting an aviary set up: I don't think it would protect Amigo against a hawk as much as you think it would. We have had a hawk break a metal chain link in our aviary with one swift chomp of his beak. If any thing, if the hawk got in with Amigo, Amigo would be MORE likely to be killed as he wouldn't have a clear escape route and would essentially be in an enclosed area with a hawk.
Just my two cents. I agree with those who suggested bringing Amigo in for a bit to see if the hawk goes on his way. The hawk is probably visiting for a bit and if he runs out of prey options he'll move on.
They pretty much screamed off and on all day for several days. Then one left and it was just one lone one that hung around for about a week and half. I watched him dive bomb squirrels and knock them right out the trees but not get them. 
