The fingering. I absolutely cannot hold the yarn the way I am supposed to and I cannot, no matter the gazillion times I have tried, loop the needle the correct way. I’ve had people watch and correct me probably about a hundred times now (no joke), and I have not once been able to do it correctly.
I can’t do the long tail in one hand as shown, so a long time ago I realized if you use the R hand to ‘knit’ the working yarn on, and slip the thumb loop off, it comes out just the same. Look at the alternative thumb method on the Cast ons page.
I also do long tail the way Suzeeq does. The way it is shown on the video is particularly hard because it doesn’t start with a slip knot. I can do it, and it is a good thing to learn as a springboard for several other good cast ons, but I prefer to work my long tail with a yarn in each hand.
I usually do it without the slip knot too, but mostly because of the talk I hear about the “lump” I’m supposedly eliminating, than for actually noticing a big difference. I think that the slip knot makes the cast on a little easier for a beginner.