Capture has 3 safety/locking features on it, and each one does a slightly different purpose. This article explains those features and what they do.
1. THE QUICK RELEASE LOCK (AND BUTTON)
The Quick Release Lock is what keeps your device (be it camera, binoculars, GoPro or lens) rigidly secure in Capture. It is your first and most important line of security, protecting your gear in even the most rigorous of conditions. It can withstand over 200lbs (90kg) of force.
The Quick Release Button is the red button that you press to unlock your device from Capture. It is a spring-loaded momentary button, meaning that it only unlocks your gear when it is pressed and held all the way down. Since your device will only slide into Capture from the top, simply pressing the Quick Release Button will not make your device fall out. You must press down the button and lift your device out at the same time.
The button is connected to a sliding pin that engages with the plate that you slide into the Capture clip. When you insert your device into Capture, you'll hear a click. That sound is the pin automatically engaging with the plate, and it tells you that your device is securely locked into place.
2. THE BUTTON LOCK
The Button Lock is a secondary redundant locking mechanism to back up the Quick Release Lock. When the Button Lock is engaged, it is impossible to depress the Quick Release Button, meaning that it is impossible to remove your device from Capture.
To engage the Button Lock, simply twist the knob of the red Quick Release Button 90 degrees. To disengage, twist the knob back in the other direction.
3. THE PLATE LOCK
The Plate Lock is a black knurled aluminum knob opposite the Quick Release Button. It's function is to stabilize your device in the Capture clip. It does this by screwing an aluminum wedge into the side of the plate, preventing the plate from jiggling around.
The Plate Lock is only used when you have a GoPro® or other type of action camera locked into Capture and you are capturing smooth point-of-view video.