I upload some videos of my programs to Youtube and get asked for the code. Since I no longer have the original code for this tree generator, I decided to recreate the program. It is very simple. The most difficult part was getting around the monkey engine that I have used for this program.
I am sure I did some mistakes (recreating the material for each cylinder. etc.). But I hope this will help the people that were interested. I published the code on github under: https://github.com/furcino/treegenerator