Lecture 14, On slide 6, the text "Child runs, sets done to 0" should be corrected to "Child runs, sets done to 1".

Lecture 15, the first slide introducing semaphores says that the up/post function on a semaphore increments the semaphore counter and does  nothing else. This is incorrect. The up/post function on a semaphore increments the underlying semaphore counter, and wakes up one of the processes sleeping/blocked on the semaphore. Every up/post call wakes up one of the sleeping processes (if it exists), irrespective of the value of the semaphore counter.

Lecture 15, on slide 3, when the child increments the semaphore via sem_post, the semaphore reaches a value of 0 (the annotation on the slide and audio say it reaches a value of 1, this is incorrect).