Demo viewer for offline games?

[caut!on]

I did some looking around online, and I was unable to find an answer. The basic gist of my problem is that I want to use the demo system for an offline game with bots or with friends, but I'm not sure how (or even if there's a way). Back when I played CS:GO, I wrote a couple of silly short stories on the Steam forums about goofy stuff that would happen in game. They got a fair amount of attention, and someone made a comment to the affect of, "can't wait for the movie of this," and it gave me the idea to recreate my stories in the form of YouTube videos. Back when I was super into this game I watched WarOwl and 3kliks religiously, and they made great use of the demo viewer (e.g. WarOwl's Road to Global and 3kliks' Going Low in CS:GO series). I'd bet if anyone would know how to do it, they would, but they are large creators and likely difficult to get an answer from. I feel like it would be easy to recreate the scenes of my stories in an offline game, and it would be nice to be able to use the third-person view for nice camera angles and swooping shots and the like.