I can confirm that. That's one of the sound stages at Michigan Motion Picture Studio in Pontiac. The crew member in the background is also wearing a Sage & Milo badge.
Yay! It'd be so awesome for the film to open with a Batman vs Deathstroke fight, he doesn't even need to be a big part of the movie or anything, just lock him up in Arkham for the next Batman or Suicide Squad movie.
Confirmed he's the villain in the solo Batman film, which apparently won't be a Raid-style Arkham Asylum film unfortunately. Also, some think Joe Manganiello is playing Deathstroke as he just followed Snyder and is currently in London as well.
There are villains I'd pick sooner, but Deathstroke is cool and someone who could lead to really sweet action scenes that other villains maybe wouldn't.
JK Simmons on Making Out With Susan Sarandon, 'Justice League' and His Secret Desire to Play a Supervillain