If your videos are on youtube, if someone copies the link they can just publish it somewhere else, or make a public playlist of all your 'paid' content.
Wistia is amazing for lead tracking and analytics about your customers' viewing habits.
Primarily, I use it for just hosting paid content in a protected way. They do have awesome lead tracking, analytics, email captures and things but your bandwidth can cost a lot if you do that too much. It doesn't quite work out financially with a low-cost screencast business like mine. Probably better for marketing teams with a budget and higher cost products.