pokinatcha
i think he means, that it's not a cross over unless it's gilmore girls related.. since it's an actor from gilmore girls playing a character on another show, it's not really considered a cross over..
yes,exactly,crossovers are like this:
let's say the Jack,Cindy and Janet from Three's Company come across the Island from Gilligan's Island and come across Gilligan and Gang, and antics commence.
a crossover is not Joyce DeWitt staring on Gilligan's Island as a character in say...one of Gilligan's dreams. cause I know there were at least two episodes like that...maybe only one?oh well that's off topic