How long is it ok to be a sage for?

So I have this quandry:

I’ve made a few Tangential videos thus far, and have met some (limited) success in the response to them. I worry, though, that despite the frenetic editing and my high-speed delivery, they’re really just a video version of sage-on-a-stage. Which is, to some degree, needed here. There’s information to be disseminated, and me talking to you is a efficient way of doing that. Also, given the nature of video, it allows students to watch multiple times to catch anything they might have missed. So that’s good. And, to be fair (to myself?) I keep the length of Tangential videos pretty short- usually around 5 minutes or so. That’s not much sage-ing, and I really intend them to be a jumping off point for class activities, discussions, projects and whatnot. Plenty of whatnot.

I had known about (but really, never watched) Hank and John Green’s YouTube channel CrashCourse, in which Hank teaches biology and John teaches World History. They are, it seems, better at it than I am. Which I am, for the moment, ok with. But these videos are clocking in at 15 minutes (plus or minus 5). Which seems like a lot of sage-ing. But maybe it’s not- and I’m not sure what that threshold should be. Thoughts?

BTW, here’s an early video from John: