This is a great video shot by Christopher Reynolds that shows a snake regurgitating a live snake.
According to Gizmodo:
So, what the hell's going on? I asked Sara Ruane, a snake expert and assistant professor at Rutgers University, Newark to watch the video for us.
"Snakes eat each other all the time," she said. "When snakes are startled by something or something is attacking them, one of their first lines of defense is to throw up whatever is in their stomach." That's because they no longer have food weighing them down, and it might scare the predator. I, too, would run away from someone vomiting their lunch on the street.
In this case, it's likely that the videographer, Christopher Reynolds from Newton, Texas, startled the bigger snake when he started filming. "As soon as that snake throws it up it takes off," she said. "Now it doesn't have this other snake weighing it down."