Link to trailers here:
http://www.gamert.nl/video/ffxiv.html
Just ignore the dutch, it points out to where the clips are I assume :)
For me, last Final fantasy I played was FFXI (that was the MMORPG one, right?) and actually never saw FFXII, but seeing FFXIII (x_x so many FF) I'm even concidering to buy a PS3 for that.
FFIV I don't know about yet. The first online one was fun to play, but never caught my attention enough to buy an extra month subscription after the first 30 days I got for free.
What do you think?