Very interesting. It shows "copying behavior" in birds. Which, with the exception of a few single animals like the dolphin, are the only other group of animals capable of doing so. (though in most other cases it's songs that are copied)
It would be interesting to see if they are able to "copy" other behaviors too. Memetics is a favourite topic of mine, and comparing various cases of how memes (which are behaviors which are copied) drive the evolutionary process is fascinating.