That's one way to secretly record your marriage proposal without getting caught. This guy pretended he was going to take your standard phone selfie, ensuring his girlfriend was already sitting close to him and smiling. Then he sheepishly commented that it was recording, got down on his knees, and presented the ring.
The result is a look of absolute shock from the now bride-to-be.
Sure, he could have hired a friend to hide out in the bushes and film the proposal, but that comes with a higher-than-average chance of being arrested, and it would have failed to capture the truly wide-eyed what-the-fuck-is-happening look in her eyes.