Actually, we've been up for something like five years at this point. No lawsuits. Our contention is that it is fair use (clearly educational, in my mind). knocks on wood
To preface this: I think the site is neat, and you're not going to be sued, and you're on good ethical footing. But: Your specific fair use claim doesn't seem particularly compelling.
First, there's no plausible risk of trademark confusion, so we're only looking at copyright infringement. The list of Seinfeld episodes, and the facts about the plot of each one, are non-copyrightable, so AFAICT all we're talking about is a single 2-5 minute video clip per episode.
The clips are a very small part of the overall episode, and they're narrowly edited to provide only enough context to demonstrate the point, which speaks to fair use. The fact that there's an educational, noncommercial purpose also helps. On the other hand, it's a swath of material cut from across the entirety of the show, with zero other sources, which is pretty far-ranging and speaks against fair use.
If you imagine cutting the clips together into a YouTube video, and distributing that, you would have an extremely tenuous case. You'd be looking for some reason the use was necessary, not just convenient. So there's actually a lot riding on that educational purpose, and unfortunately that seems like the weakest part of the argument.
Here's the rub: The site isn't educating people about Seinfeld. It's about economics. While the clips make for compelling examples, no one could reasonably claim they're the only or best ways to make those points. In other words, it doesn't seem like there's any reason you need to use material from Seinfeld instead of almost any other piece of popular culture. That runs a big ol' hole through the educational purpose argument; fair use isn't structured to let you copy whatever you want to, and simply being a teacher doesn't give us license to infringe at will, alas. (Educational institutions have a substantially more circumspect understanding of fair use[0] than Reddit does, and for good reason.)
Keep in mind the educational exemption applies much more strongly to private performances than reproduction and distribution. I'd guess a university-level, semester-long course titled "The Economics of Seinfeld" where students watch a clip every class day would have a rock solid fair use case. But if the professor starts handing out DVDs, that starts to look like a place where the rights holder would want to draw a line in the sand.
Anyway, again, for my part I see no moral issue, and I didn't really intend to belabor the point this much, just reasoning through the logic of fair use. I assume you haven't been sued for more blasé reasons than your use being legally defensible, to wit the Web double whammy:
1) Your infinitesimal damages are far below the cost of even sending a C&D letter, and
2) Suing any fan site, let alone one for a cult classic that's still showing reruns after fifteen years off the air, is clinically insane.
Yes, as you say all educational uses are not "fair use" in USA (from my understanding of the USC as a non-expert non-USA'ian) - this is unlicensed derivative use of copyright works AFAICT. They're not even that derivative, the example I looked at seemed to be pretty much just an recut version of the show (without credits and such of course).
If someone ripped the site and added an extra line of comment to each page would the authors of that site consider it copying? The site is a very thin wrapper on the content IMO, like copying a book, cutting out the foreword and adding a new dust-jacket.
Trademarks: You don't need actual confusion to be infringing a registered trademark in USA. Even when there is definitely no actual confusion you can still "infringe" a mark, cf Trademark Dilution, 15 USC 1125(c).
[If downvoters can cite USC to show any factual errors that would be helpful. If you just disagree that this use, eg feel this should be allowed use, it helps to say that too.]
I didn't (and can't) downvote you, but if I had to guess it's because your comment didn't add much content, but has a very negative tone. HN likes to see commenters being constructive, not just correcting. (And keep in mind that things you write on the internet generally read as more argumentative than you intend them.)
