I haven't watched the video and I'm leaving off grid for the weekend so I'm afraid I won't be much help on the matter. Demo, in terms of taking down a whole building isn't something that most architects would know how to do. It's definitely a specialized field, since the majority of architects and engineers are in the business of trying to keep buildings up - not tearing them down. In terms of structural capacity and fire strength of the steel, what I can tell you is that material testing is typically done in a lab without any unknown externalities so that what can be learned is reduced to a very small quantity of environmental conditions. This testing is what allows people to guarantee performance and state that "this building should act this way". Once a building or material enters the real world though, there are contingencies that can never be planned for. Starting the day the material is produced, it is susceptible to so many variables. For example, what kind of intumescent paint was used? What is the shelf life of the paint? Was the steel primered in shop or on site? How much exposure did the building have to water? Pollution or exhaust? How long did the material sit on site before erection? Was the building fabricated to spec? Was it constructed to spec? Were the welds tested? Was the concrete tested? What was the outcome of these tests? What about seismic testing? Any little thing that can somehow compromise the integrity of the steel material, fabrication to construction should be questioned because over a long enough period of time, a seemingly small imperfection in material integrity or maintenance could have large built up consequences. Some of this stuff may have been covered in the video, I don't know.

Looking at the comments, I agrees with zebra2. The main question is "What would be gained from this?" I don't think anymore than if just two buildings went down.