Lexie, I laughed and laughed! I've seen that tail-shaking thing so many times from the horde of squirrels here, very familiar w/that sign of stress.
But what I really want to know is how did he cling to the glass of the window? I mean, at some points he clearly seems to be just walking right up the glass a la Batman, not hanging onto the frame or any other protrusion!! If my squirrels ever develop that ability, I am throwing in the towel and moving someplace that has no rodents, indigenous OR imported (is there such a place?).
Just this AM I watched a squirrel creep out the horizontal pole holding my suet feeder and hang down off the pole. He found himself unable to crawl down the too-thin-to-climb-but-too-thick-to-flex wire to reach the feeder but saw that he WAS able to hang by his back feet and reach the chain attaching the feeder to the wire hanger. He then hauled the suet up, hand over hand, using the chain.
About the time he got it to his face, I screamed at him "put it back, you little $#%@^!!" and he dropped the chain and launched off the pole w/a leap much like the one in your video. I just went out and removed the chain and lengthened the wire--the battle continues.