Huh. I just learned a new knitting technique from Reddit, of all places! Rather than weaving in all the ends from your fairisle colour changes, you leave them long and then you essentially French braid them down the seam on the inside.
What the video doesn’t show is what happens at the end. Presumably you have some length of braid from your last few changes, and you… what? Put a rubber band on the end and have it hanging outside your sleeve? 😂 I’m guessing it’s something like: “fold it back on itself and weave the last few bits back into the braid,” but it’s annoying that they didn’t cover that bit.