That's in Red Faction too. Just different colors and more smiley. Just a developer test image.
The BS2 files are similar to BSP, only a few different lump sizes than BSP.
You can open all the models in ModelViewer, too, just rename the dol to mdl. The textures are all screwy, but you could reskin them, or write a program to view them and then they would look OK.
Useless fact: .dol is named after Matthew VanDolen, a Gearbox coder.