No, everyone can be choked.
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So far, everyone who competes has shown themselves to be chokeable. Jon Fitch was notoriously resistant to being choked out...until he was [guillotined into unconsciousness by Josh Burkman][1].

The video is a lame, contrived demo. The choke is not performed effectively. It's a farce of a choke. The reason this strutting bodybuilder is "immune" to the choke is that it's not a legitimate choke in the first place.

Strong necks can resist poorly-applied chokeholds and can, to a minor degree, prevent the attacker from getting into position for a good choke. But so far, everyone has proved to be chokeable. People can have good choke defense just like they can have a good guard, but so far no one has shown themselves to be "immune".

  [1]: http://www.youtube.com/watch?v=VXl_YEsxR-I