Wish I Could Undersrtand "Hummingbird"

I have had the best morning watching the birds and rabbits in my back yard.  The hummingbirds have been particularly entertaining this morning.

One hummingbird in particular has  been cracking me up.  He is very aggressive and does not want any other hummer or bird around while he is feeding.

He was sucking up nectar in his feeder ,which  is about ten feet away from the bird feeders ,when a couple of purple finches came down to feed.  The hummer immediately flew over to the finches, hovered about a foot away from them and obviously had a "conversation."  Within seconds the finches left and the hummer went back to feeding.  The finches did not come back until he left.  What do you think he said to them?