I have absolutely no idea what is going on here. Normally you can kind of derive some semblance of understanding out of a commercial or television program just by watching it, but I have no clue what deep sea fishing and Dragon Quest IX have to do with each other. That being said, and to completely contradict my first two sentences, I think I've got a clear picture of what's going on here.

See the fisherman wants to catch some Poorly Dressed Japanese Men (PDJM) to take them home to be his slaves. Since the Japanese love Dragon Quest he uses it as bait. However, once he catches one the rest want it too and he has no idea how to handle five PDJM and so he runs away from the commercial. Things start getting crazy then. PDJM 1, who originally caught the game, swallows it and his life must be saved by the rest of the PDJM team. However, once that is done the Japanese's insatiable hunger for all things Dragon Quest takes over and they leave him on the deck alone and go off to play their DSi.

To summarize: The Japanese are crazy about Dragon Quest and it doesn't matter how insane the commercial for the game is, it's going to sell better than rice.