This is my solution for an installation where the visitor can pause a playing video by making a stop sign with their hand. The video will resume when the stop sign is no longer detected.

You can switch between the available webcams with the left mouse button and show/hide the webcam with the right mouse button.

Because I couldn't find a way to pause/resume the video, I used the 'speed' socket to toggle between 1 and 0 speed, which works perfect for my goals.

Because the hand tracking sometimes wouldn't start working, I added the timer in the top right that keeps refreshing the hand tracking until the webcam works. I'm sure there is a better way to achieve this.