...except for video that is re-cut to 16:9 with letterboxing at 31fps, then all the pirates will just encode it that way and evade the filter...

If they do it right, the filter can be more sophisticated than that. Yes, pirates will be able to evade the filters through some combination of transformations, but it's possible that the resulting video will be unwatchable and/or barely recognizable.

Would you want to watch a movie that had been inverted, time shifted, and played backwards?

Not surprising --- looks like a power law distribution. These are very common in all kinds of human/social/popularity scenarios.

PARTIAL SPOILER ALERT

#18: Think modulo

Generalized-

How many gnomes must die when there are n possible hat colors?