After watching the video, I believe its important to drug test before hiring and have random drug testing periodically.
My last employer, who does drug testing before hiring, was so confident of this particular hire, that the company let him start work before the drug test was finalized and the test results sent over.
He probably worked a couple of months and I'm sure it didn't take that long for the results, but he failed the test. He was a driver that worked in the warehouse so instead of letting him go, they moved him into the office behind a desk.
When the company needed a driver because all the drivers were out or it was a rush order for a delivery they used him.