Spock is alive on the Enterprise, hiding on the other side of the planet from Khan, and dies later in the film, after retrieving Kirk and participating in the ensuing space battle. Right youtube link, though.
You might be confused by it's counterpart in 'Star Trek: Into Darkness' (also represented by this service), where it's said by Spock on Kirk's death.
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[0] but one which is explored more fully in a set of recent "prime universe" comics: http://memory-beta.wikia.com/wiki/Khan:_Ruling_in_Hell
JAAAAAAAAAAAAAAAAAAAAAACKSOOOOOOOOOOOOOOOOON!!! http://khanaas.com/kirk/jackson/
BOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOB!!! http://khanaas.com/kirk/bob/
though, maybe Bob is a bad example :)