AFAIK an incandescent lamp turns about 90% of the energy it consumes into heat, and a CFL about 30%. So a 20W CFL will produce, not as much heat as a 20W incandescent, but as much as a 7W one.
He is therefore suggesting that an incandescent lamp will generate roughly 3 times more heat than a CFL of the same wattage.
Mind you, as bernard pointed out, with a CFL the heat is mainly generated close to the base, not all over the envelope - so , particularly if it is installed 'base up', the heat will probably not be dissipated as quickly from a CFL. That might suggest that the base of, say, a 60W CFL would get hotter than one might expect (from 'heat watts' alone), but probably nothing like as hot as the envelope of a 60W incandescent.
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