You are quite correct in saying that there are no lectures on Pecking Order Theory, and there never will be!
There are no numbers involved, and so if it is every mentioned in the exam (which is fairly unlikely) it will only be a small written part.
I assume that you are watching the lectures together with the Course Notes (it is pointless to use either on their own), and if you look at point 6 in the chapter “The cost of capital – the effect of changes in gearing” in our free Course Notes, then you will find all you need to know for the exam about Pecking Order Theory 🙂
All it is, is that firms will raise finance in the easiest (cheapest) way!