I haven't reviewed the videos above, but I understand guavas are supposed to be difficult, but possible, to root. And that usual methods are grafting or marcot/air-layering.
I have seen two methods described on this forum for rooting guavas, the "bag method" and the "solo cup method".
Because I received some cuttings from Kaz but had no good place to graft onto, I am doing the solo cup method on some cuttings. I was having good results, but my 1yo son knocked them all over last week and spilled the soil... so they might die now :-/