Watched it for a half hour. I'd go with the doc as well, but from what I watched, he never described the mechanism of action of cannabis. The book writer was full of shit, and as swarthy as he was, made me believe that his real objective was to cause problems, and controversy. What he's doing is trying to raise a shit storm to make money.
The conversation was like this: as the temperature rises more ice cream is sold, therefore ice cream causes the temperature to rise. Any evidence that co2 is related to global warming is admittedly ignored.