Is it normal to "forget" the methods used on the videos? I'm currently watching the binary exploitation playlist(more than 30 videos already), and while I do understand the concepts(let's say 80%), like stack, heap, nop slides, ret2libc, how the kernel works and the way he exploits on each episode, I can't remember  how he exploited on the videos that I watched, let's say, 3 days ago, eventhough I did understand and if I watch it I can "remember" again.

 I am doing something wrong here? I feel like I'm running in circles, or maybe going the wrong way.

Let me say too that I'm using LiveOverflow videos as a first point to learn exploitation, only after I pretend to jump into books.