Just got 42 letters of that sort of warning and they're all S4U, in-game vids and the Jupiter CD content...Even the fanmade vids are being copyrighted by Bandai. WTH?!
Basically, anyone who understands anything about DCMA will know that it's effectively nearly impossible (at least on a medium to large scale) to keep safe harbour provisions and review every single possible infraction in the time allocated (It's 5 days from memory). It's easier to take down first, then ask questions later.
If you fail to challenge it, they are required (by US law) to take it down by the end of the period. You can counterfile, and if the other side doesn't reply in (I think) another five days (Namely with their case), they're required to let the contested video stay as they've conceded the point. They're in their right minds permitted to just go 'Fine, we'll take you to court' so it can be risky unless you really know where you stand.
Now, in a sane world, you'd think that any mistakes by youtube would just apply to any videos where it's been let through.
No, if you lose safe harbour by failing to comply with a single case, you lose it. Period. In short? Line up the lawyers, they've declared it Youtube suing season, and youtube can't do much about it if they lose the provision.
So it's actually in their best interests to automate the process as much as possible, because one miss is enough to get them blown out of the water.
So consequently their heavy preempting. I guess they've just conducted a periodic sweep with their new detection engine.
Note however, that it usually requires a takedown (for fair use cases), unless you're asserting that the material is substantially yours and/or you have acquired reproduction rights. (It's incredibly unlikely anyone here would fall under the catergory) since a non takedown will just redirect any ad money (if there is) to the content holder.
What does this mean? If you know where you stand, then find the paperwork then file an appeal (Assuming you know what the bounds of fair use are) which then gets forwarded on from Youtube to the content holder in question.
Of course, if you're wrong, their lawyers WILL eat you alive, if they decide to contest your counterclaim, because it will be played out in court.