I watched the first video and two things I don't agree with - he plans to have 3-4 ball pythons in his 40 gallon eventually and he recommends changing the substrate every six months. With all the urine that he can't possibly get up - once a month would be more appropriate.
To the OP - I suspect that since both animals came from the same source, they were already sick. I would completely throw out the equipment and housing that you were using for these two and start over with a tub set up for a more economical solution and purchase a ball python from a breeder, either to be shipped to you or find a breeder that is local to you.
oh my!!!! How could i forget???!?!?!!? its the best one out there!