So turns out it was extended clips from what they said was the first 3 episodes
Overhaul's meetup scene with the LoV, All Might bringing in Mirio to introduce Deku to Nighteye, and Deku actually meeting Nighteye and the first half of their whole encounter
Kind of disappointed it wasn't just the full first episode but whatever there was good stuff. Although I have been hearing about the premiere being an original recap episode, and that would kind of line up with saying what we were showed was "stuff from the first 3 episodes"