What is this in the newer Zombies Labs trailer?

[jimbob200521]

http://www.youtube.com/watch?feature=pl ... 4j24#t=79s

That should be to the right time, maybe you have to go back a few seconds but it looks like it's in the lab and something is going through the ceiling to the floor and beyond. I don't recall this happening in the actual game, during the Easter Egg or otherwise. Please point out if I'm missing something obvious, otherwise wtf is that?

[MixMasterNut]

It's the excavator coming down in the tunnel by the PM63 wall pickup.

[jimbob200521]

It's the excavator coming down in the tunnel by the PM63 wall pickup.

Ah, never looked at it from that angle because, well, now that I think about it, I don't think the excavator has breached that tunnel since I've been playing moon. If it has, I've never looked at it.