Best camera for shooting wildlife photos?

I was thinking of buying a Canon eos 5d mark II, but I want to if there any other good cameras. I am willing to spend up to 4000 dollars or less. Oh yea and another question, what is that huge camera lens at 0:18 in this video?

Its not necessarily about the camera you get. I’m pretty sure any DSLR camera can do wildlife but its more about the lenses you get. The lens in the video is most likely a Canon. Probably a 400mm. (just a guess)