Click on the picture to see and hear playing across the window.
Other whistle tricks? 
Cool! I’ve done that a couple times but never with the tone you’re getting. A trick I did during a performance was to play “Rhythm whistle,” where I got real close to the mic and slapped the holes to make a sort of “plipping” sound to the tune of Fig for a Kiss. Works best on descending notes but you can do ascending if you “strike” the note above the one you want to sound. Not as cool as playing a guitar behind your back, but equally difficult to do well…
Well done, good tone from such a rotten embouchure hole!
You can take the plastic head of a mass-produced whistle and play on the body tube alone, using a Kaval embouchure (blowing diagonally across the tube end). Needs practice if you never tried Kaval playing.