That would be an ABSOLUTE nightmare to clean and maintain. The dirt will flake off whenever you even try to clean it. And forget about disinfecting that enclosure...not possible with all the semi-loose dirt and nooks and crannies. Not to mention that flooring adhesive is far from non-toxic, especially when heated.
There are other ways to achieve that sort of look...all of which are safer. Read up on creating grout rock structures...with painting and grout, you can make a real looking rockwall. Its not that hard, and will be much more durable then whats in that video.
yea its alot easier.. i've made a fake rock wall and platform/rock takes days... but still the guy who posted the video in his comments said he paid $400 not including lighting/heating not even worth it. one 4x8 styrofoam sheet 1 1/2 cost $5 premade grout $7 and woodglue $4 paint $8 and sealer $9 all so about $38 after tax and i was able to make a fake rock wall and 2 platforms...