Like many others, it ticked me off when I first saw it, and I dislike it being continuously trotted out by folks who don't 'understand' how it offends people. I like gnomes. Quite a bit actually. The video was made BY the people who took away the gnome I and my friends liked, and then made fun of the pseudo-gnome they propped up in his place. It's got a whole "nah-nah-nah... In your face, loser!" childlike vibe to it.
That was my reaction when I first saw it, and it was similar to the reaction of the rest of my game group. Personally, I want that video to die in a fire.
It was the same as back a while when folks were complaining about not getting enough gnome figures in DDM. So on April Fools, they had some garden gnomes, it was all a good laugh....
Except, like this video, it doesn't address gnome fans seriously, instead showing utter disregard for them, really. It's not a matter of "listen, we appreciate that you like gnomes, but when we needed to make room, they didn't make the cut". It's "I'm a monster, roar!".
It's a mark of 4e. If they can't figure out how to do something, they simply cut it or bump it to a different book. "You can play a gnome, just buy <insert next book, MM or PHB2 or whathave you>" or have a friend send it, or ask the DM...
(I was actually surprised that the gnome wasn't immediately released as a web enhancement for the PHB.)
The funniest part of the video was how Draenei-ish they made the tiefling. The accent, even. (But, if it was intentional satire, then they failed the perform check, or I failed my Insight roll, or something.)
So, yeah, the "You've got Mail" quote about fits. If gnome-fan's generally find it an insult, and those applauding the anti-gnomite 4th edition also find it quotable, then we can see where it fits.
The fact the Forest Gnome is now the official gnome, rather than the older Gnome of Inspiration, just means that they REALLY don't get it.