This is a long video, but I especially recommend the section starting around 8:18, through the shadow movement that’s replayed in slow motion.
Could it be confusion about normal shadows? Possibly. With a variety of light sources and multiple people in the room, it might even be likely.
However, there’s a quality to the shadows — though I’m pretty sure one part of the image is normal — that seems downright peculiar to me.
The video is long (too long, without some video notes or a good transcript) but includes other possible anomalies, as well. If you have time, watch the whole thing, since it gives you a better context for evaluating the anomalies.
The site is an office building in Harlingen, Texas and the investigators are Graveyard Shift Paranormal. (As of March 2018, their website seems to have vanished.)
In general, the lighting and reflective surfaces (glass, mirrors, etc.) at the site are definitely a problem. If that were my video, I’m not sure that I’d feel confident of any anomalies in it. I’d go back with black sheets to cover every reflective surface, and I’d have extra cameras set up behind the cameras that are filming possible anomalies. Those extra cameras would be a way of double-checking (or “debunking”) anomalous shadows, based on who was where, and what lighting was involved.
I am a little skeptical.
However, there’s something about that shadow, and how it changes shape and moves… We’re looking for “weird within weird” in many videos, and — in my opinion — that qualifies as something for further research. The shadow might be completely normal, but it’s still very, very odd, and that’s consistent with some shadow figures we’re seeing during ghost investigations.