Evolution of Batman Symbol over the Years

I remember myself doing so many of them when I was a kid. I used to be crazy about Batman and his world, not jut his accessories. All my books used to have the symbol somewhere or the other. Atleast on the rear. I am not sure who made this video, but a nice example of branding, which has always evolved so much. I dont think any other superhero's symbol is as great as Batman's and which have kept on changing.