HI. I watched CHAD only once and did pretty well on my science. (BIO 23, GC 24, OC 20)
I watched each section (you know, the 2 hour bundle of playlist) per day. As he went on, I wrote a note on a scrap paper. After the video, I re-wrote the note on a separate note. If I didn't know what the topic was talking about when I was re-writing, then I went back to that section again and re-watched it.
For Bio, Youtube's Crash Course (free) was better and more detailed (and animated too).