I was looking for videos of Alex, the african grey who could count, seemingly understood concepts, etc... and died a few years ago, and found this which I thought was pretty cool. It has bits on Alex, and his successor Griffin, and Einstein.
It is really hard to train a bird to talk, let along to "talk smart". It must have taken years and a lot of efforts for even an extremely experienced bird trainer to achieve what we see in these videos. If I have a bird like that, I'd definitely when he/she dies.
Did the same trainer train all these African Grey you named?
I can't remember the ladies name, but she had Alex for over 30 years. I saw him on PBS 20+ years ago. He passed in 2007 or 08. Apparently Griffin(?) is one of her parrots too. And I don't know much about Einstein, but I've never seen videos of him adding, answering questions about what something is made of, etc... He just responds to triggers with a sound. I say "just" like it's that simple...
Yeah, of course these talking birds don't really understand what they are saying. It is just condition reflex from the training. They respond to certain words with certain words. I read it somewhere a while ago, that one of the hardest parts in training a talking bird is to correct bad behaviors as soon as they appear. Or the birds might say things you don't wish them to say.