Note how that's not a DMCA notice in the usual sense ("we own the IP of content distributed on your platform"), but a "strongly worded letter" that mentions the DMCA but just says "we'd like your assistance in stopping this illegal activity". At least it's not run-of-the-mill DMCA abuse.
It's interesting that GitHub decided to process it like a DMCA notice, unclear to me if they had to, and even less clear if the counter-notice is meaningful.
This is one of those cases where I bet Github's ownership is in play. Github the company may not care about what the MPA thinks of them and could consider fighting this. Microsoft I'm sure have at least some business linked to the film industry and do not want to poke the bear.
I'm not a lawyer, but I believe this is an actual DMCA notice. It has all the required components[0] of one. Is there something I'm missing? What makes this not a DMCA notice?
It's not at all clear that they have identified anything on GitHub that is a copyright infringement. They've correctly claimed that the software is being used elsewhere to accomplish infringement, but the URLs they identified aren't reproductions or derivative works of any movies.
It's interesting that GitHub decided to process it like a DMCA notice, unclear to me if they had to, and even less clear if the counter-notice is meaningful.