Transmission Sound Question

[Afboy143]

So I was reading on RPS.com and I found this video

http://s11.photobucket.com/albums/a1...t=DSCF3117.flv

Someone asked " why does it sound like it has a blower on it?"
The guy replied " thats my transmission, if you take the little rubber thing off at the bottom of the boot, the sound of the gears is 10x louder" What exactly is this and where is it located?

 

[E-rock]

dead link

 

[Afboy143]

whoops

http://s11.photobucket.com/albums/a170/Alan0110/?action=view&current=DSCF3117.flv

there

 

[99SportX]

I am going to assume this only can be done on a manual trans? Because the automatics have no form of boot on the trans. I know nothing about the parts on the explorer/ranger manual trans though, so I can't help in that respect.