I can't say that I'd go through the trouble of finding specialized canned tuna, but it was a good attempt by Alton Brown to utilize everyday foods. The tuna dressing sounds good; I'd probably use it for a cracker dip and add a little hot sauce. The croquettes remind me all too well of salmon patties which I can't stand, but I'm sure the taste would be more along the lines of the tuna dressing with crackers with panko crumbs added. I was hoping for one of my old, simple, favorites: cream tuna on toast. You can easily get by with 'regular' tuna and it might have been a good demonstration of making a basic white sauce.
On the entertainment side this episode was a hit. The Charlie Tuna knock-off was brilliant and really added to the informational dialog. The twin Alton MIBs, coupled with the pregnant lady chowing down on potato chips (my wife was in that state not too long ago), was a great way to go in spilling the story on mercury instead of just a short interlude. I also detected some Popeye themed music in the background which instantly made me think of Jean Claude trying to stomach the canned spinach in The River Run!
On the scale of creativity, science, and pure entertainment we've come to expect in a Good Eats episode: I'd rate this one pretty high. The culinary aspect could have used a little improvement; I know Alton can do better than tossing together a salad.
p.s. I'm still fighting my Dutch baby addiction which has lately been strengthened by my new iced coffee addiction :-)