Emus work just like the psx so you´ll have mem card data on a file in your computer giving you more versatility. If you´re trying to create some kind of video then that I wouldn´t know, but exchanging replays is easy just give the file to someone and they can view it by loadind your mem card on their emu.
There is inclusively a program to converts mem cards from other emus and even dexdrive saves. Thing is the version of your gt2 copy has to be the same type (PAL, japanese, NSTC) wich leads me to another issue: I´ve been trying to exchange replays with gamers but no one so far played gt2 in an emu using a PAL version so... What´s your version?
One last thing, I belive most gamers are unfamiliar with the fact that they can use gameshark codes on their emus. Just download a neat liitle program called PEC (playstation emulator cheater) and you´re set.