Trying to attack this game with copyright is not a good idea. While I'm not sure what he is doing is fair use, USA fair use is much fuzzier concept than Warp wants it to be. With Warp's definition, none of our encodes would be fair use either, and we would have no defense against lawsuits by Nintendo etc.. But thankfully fair use is a bit broader than that.
Here is a guide that helps you sort-of-guess whether a video is fair use or not. Sadly, the only way to be sure seems to be to settle the issue case by case in court, because fair use is basically a set of commonly recognized excuses for breaking copyright, not actual limitations on copyright itself, as it is in some, saner, systems.
To summarize the article, factors that matter are:
- How transformative the work is. His case is probably pretty low on the transformativeness scale, but it does set the TASes into a new context by showing only their ending.
- Whether it is commercial or non-commercial. Being non-commercial helps. In this case I guess it would help him if he doesn't get advertisement revenue from the videos.
- How creative the original work was. A collection of statements of facts has less protection. In this case the original was creative enough to qualify, I should think.
- The amount and importance of the part copied. Only a small part of the video is copied, and an even smaller part of that actually includes TAS input, typically only a few seconds. This would be the strongest fair use point, I think. Most of the video is taken up by the ending, which does not have any creative input from the TASer.
- The effect of the work on the market of the original. It would be very hard to show that these ending videos make the original TASes any less interesting. In fact, they may have the opposite effect by making people want to see how the rest of the game is played, not just the beginning. This would also be a strong point in favor of fair use.
I am not sure how this would turn out. He has a few points in favor of him, but does not qualify for all of them. You don't need all points for it to be fair use, though. How many do you need? That's up to the court to decide, sadly. Because fair use is so horribly vague.
In addition to all this, I think getting worked up about this is small-minded and unproductive. It is flattery that this guy chose your videos rather than other videos that could have served the same purpose, and he is not harming any of you. He is lazy and not very competent - that I agree with - but the copyright angle is not worth getting angry about here. I think the biggest issue with his videos is, like FerretWarlord points out, that they often fail to show what a typical last boss battle is supposed to look like because he doesn't know the game well enough to choose appropriate videos.