There's a few other things to note in the video:
- There's a rough shape of a humanoid holding 2 sticks or weapons on a wall to the topleft, kinda looks like graffiti.
- There's a rather onimous looking cloak in the middle of the room which has a tiny bit of movement. You can see both of these in this picture:
- Near the end of the video, there looks to be someone behind bars holding something or someone. And then just before video ends, they're no longer holding anything.
This trailer reminds me of when they first announced Mercs 3D and they had the silhouettes of the entire cast, and you could tell by those silhouettes who each character was (and they weren't all officially revealed until a half year later). But I doubt there's something crazy like that to be found in this. Still neat they released a trailer like this with many hidden clues and references though.