"Black midi" as a term refers to a musical art form that's not exactly the same as a musical genre. It is instead a reference to how the music appears on screen in a midi sequencer. Some midi sequencers are little more than elaborate spread sheets with rows for individual notes played by specific instruments, and columns that represent whether or not that not is being played at that moment. "Black midi" (the art form) refers to music that is composed in such a way to be interesting in the sequencer view. The name refers to when the whole sequencer is full of notes but the art form includes more creative endeavors (which generally sound better than all notes being played at every interval). Some times these tracks are arranged in more of a Guitar Hero, Rockband, or player piano format.
"black midi" the band is more of an homage to this format and you can expect going into this album lots of noise, lots of sound, and even a 'Wall of Noise' effect. Reminds me of some early Flaming Lips.
Good luck!