What is the most dificult lesson in you ever found here at Lingq?

for me is that Login - LingQ

Even native English speakers might have trouble with something like that.

It is funny. I found this lesson two days ago and I though I’ll never be able to understand materials on that level. After 5th session of listening I realized, that it was only my own mental barrier. Still I do not understand whole text, but each try helps me to find something new. Maybe I am no master yet, but thanks this site I know right direction.
Any other ideas of extremely difficult lessons available here?