I didn't see how they did the testing in the trailer. I do remember one test where chimpanzees were subjected to marijuana smoke being streamed into their nostrils constantly for something like 20-24 hours in late 60's or early 70's. Smoke being streamed into your lungs, you can't get much oxygen...of course those poor chimps ended up with lost brain cells. I use CBD oil myself, I have MS and the pain is absolutely unbearable at times at it helps.
Do watch the full movies over here:
I couldn't remember exactly how it was done, but lack of oxygen was definitely the culprit...I have more damage to my brain cells from MS than a regular smoker.