Couple things to note:

* He does have flux in the crown already, along with some brass. He knows when the steerer/crown joint is up to temp when he can see the brass flowing out the crown race seat end (bottom).
* He's using a "big ass tip" (a small rosebud). That's pouring a lot of heat into the crown in a short time.

I think it also depends on how your jigging works. What access you have, etc.

My method: I generally do a two-step process (well, three, because I'll often put a plate on the bottom of the steerer to close that off). Brass on the steerer to crown, and then silver on blades to crown. I use a #4 tip with oxy/propane, and it gets the job done. I like to be able to feed brass into the crown/steerer joint through the blade openings. I also drill the steerer to vent through the crown.