Can Tunnel-Up belay method Fail? Testing the Limits

How Risky or Not Risky is to Tunnel Brake Hand Up when you are taking Slack during Lead Belay? I have seen many arguing about this, so decided to do these experiments... so many can argue even more :D Massive thanks to my friends who helped to film this episode: If you are getting value out of my videos and wanna feel good - consider supporting me: Because that makes a big difference and is the main reason that allows me do this project! Deep Thanks! Ben