What is happening?

[Spizzico]

Baseball Video Highlights & Clips | SF@TOR: Buck makes a grab by the dugout - Video | MLB.com: Multimedia

What is happening?

WHY THE BALL IS DEAD???

"A player is not permitted to step or go into a dugout to make a catch.
A player is permitted to reach into a dugout to make a catch. If a
player makes a catch outside the dugout and the player's momentum
carries him into the dugout, then the catch is allowed and the ball
remains alive as long as the player does not fall while in the dugout"