In video number one he says he began following
Jemaah Islamiyah after a secular upbringing.
Jemaah Islamiyah - Council on Foreign Relations
The radicals, led by his mentor, Dr. Ayman Zawahiri (OBL's #2 in command), were allowed to gather, organize followers and pray in a room in the medical school in Cairo and it grew to a mosque then a library and ultimately appx. 1,000 people were members of the Jihadist group.
He points out that poverty isn't the reason for the terrorism, it's the teachings of the Jihadists. Most of the medical students and staff at the medical school were at least middle class and not impoverished. Also, if poverty caused terrorism why don't we see Christians, who also live in the region and are as affected by poverty as Muslims are, performing suicide bombings?