From looking at the video, the birds appear to be MH-60s and A
H/MH-6 Little Birds, which would almost certainly make them part of the 160th Special Operations Aviation Regiment, The Nightstalkers.
Now, I’m not upset that they’d practice flying in a civilian urban environment. They fight in them, so they need to train in them. But the passion for secrecy in special operations means they apparently never even alerted the local media or filed a Notice to Airmen for the region. Scaring the crap out of the population (and furthering conspiracy theories among the nutty) are not mission enablers. And if there had been a mid-air with a civilian light plane, the Army would come out looking pretty stupid.