Not a chance this is real. The guy has either done the TacRespawn thing with a friend, or is just really quite good.
Multiple times I have been Nuked randomly by someone who nobody ever noticed, usually camping with a Heartbeat sensor and cold blooded.
But if, in the 1 in 10,000,000 chance it actually exists, Modern Warfare 2 is going to be a very different game in the future.