MyGymbox workouts on Roku box

I recently found a channel called MyGymbox on my Roku box (a streaming internet device) and it has tons of workouts. The problem is that every one I start that says 30 minutes stops in 2. When I press play again, it starts from the beginning. It gives no indication that I need to pay for the particular workouts I chose. The "subscription" ones seem to be in a separate area. Has anyone ever used this site and have you had a similar experience?