He seems to be going out of his way to say that carbs are necessary, nobody should be arguing that they aren't. For someone who is say zero carb for simplicity, the liver breaks down fat into fatty acids and glycerol. This is totally outside of the cycle he is speaking of by the way, he seems to state that the only 'burning' of fat is in this cycle when in fact the liver is breaking down fat all the time. The fatty acids are then broken down into ketone bodies in a process called ketogenesis. The glucose byproduct can then be utilized in the muscles or stored in the liver for further use, or if there is extra it gets converted and stored as fat. People seem to miss this fact a lot. Once this is done his process comes into play.
So, for our person who doesn't eat carbs, they generate their own carbs needed for various functions from the breakdown of fat, which in turn loads muscles, fuels the Krebs cycle and all that. Does fat need the carbs to perform the functions he mentions? Yes. Do you have to eat those carbs? No. If fat is supplying carbs to run a process that burns fat you can just as easily back up a step and say to get the carbs for his "carbohydrate flame" you must create them by breaking down fat (or eating them).
4:50 just shows a complete lack of understanding of the science, he can regurgitate words from a book but he doesn't understand the process. Anyone with even a little knowledge of keto knows we can create our own carbs, and that lean muscle mass is not the only option. Poor fasting folks just wasting away to sticks because they aren't eating sugar (rolly eyes).
Sad that so many people have watched that crap.