So, you have a few minutes of introduction, then a quick preview of whats coming up, then an ad break. Then after the ad break, they show you what you saw earlier, a quick little update, and then another flash forward to what you'll see coming up.
You left out the part where the flash forward is often misleading and designed to make the next part seem more interesting than it really is. So you start the show with an exciting preview, then a bit of content, then another exciting preview. Then ads. Then a recap, then the discovering that what looked interesting in the preview was entirely uninterested followed by another deceptive preview.
But MythBusters does it even more annoyingly: they'll combine Adam and Jamie doing Myth A with Tori, Grant, and Kari doing Myth B. So you end up getting those little recap, content, preview segments first for Myth A and then for Myth B, followed by a block of ads. It makes the entire thing completely disjointed and pads out what should be two mini-episodes into a single 45 minute episode.
I've kind of wanted to take a MythBusters episode as aired and edit it to remove the preview/recap stuff and merge Myth A and Myth B into a single block of content and see how much content I'm left with. Except I'm too lazy to bother pirating an episode to do that.