If you watch the full video on YouTube, his right hand is fixed the entire two miles except for a single thumb flex. His normal looking left hand is much more mobile and fiddles with the frozen right pinky. This guy appears to be CAT or Counter Assault Team. They engage the threat while the Secret Service whisks the POTUS into the Beast. I'm thinking his real right hand is on a full auto SR 16 with 100 round Beta C mag or something a little more serious.