It's easy, according to someone who's done it. In a second clip currently in the possession of Toronto police, the videographer behind the infamous, still-sealed Rob Ford crack tape "advises that to record someone secretly you should aim the camera towards that person and they won't know what you're doing as [you're] just playing with your phone" — and they're busy smoking crack — according to documents made public today. "He then advises that's how you would catch a person slipping. He then goes on to say 'or even catch a Mayor smoking crack.'"
In the more noteworthy video, as detailed in the documents, "Mayor Ford holds the glass cylinder to his mouth. Lights the lighter and applies the flame to the tip of the glass cylinder in a circular motion. After several seconds, Mayor Ford appears to inhale the vapour which is produced, then exhale vapour." Yep, sounds like smoking crack.