Saw a few posts about this so I tried to slow it down and brighten it up (sorry for the sucky quality) but it does look like it could possibly be Kate. 

1) In the first gif, you can see someone’s forehead over Seth’s shoulder.
2) Red hair visible in the second gif
3) It looks like the outfit Amaru was wearing before she left Kate’s body.
4) Someone is holding that sword (?)