That's the reloading room/indoor range/rifle of Saeed, the owner of the Accuratereloading site.

The T-Rex gives FPE in the 8-9.5k range.
I forget the specifics on that particular rifle, but I think it's a fairly light sporter.
Saeed has a 'hall of fame' collection of vid clips on his site of each of his friends and guests who've taken the T-Rex on for a shot or two.

There's more detail on the AR site.
Pretty entertaining stuff.

--Tinker