Thomas was in the house as a guest of the team, which honored his 52-point performance against the Miami Heat nine years ago. After the video played, he let out a scream himself as the camera panned to him on the sideline. If this was a Disney movie, we’d cut to an outdoor scene where a bolt of lightning would hit TD Garden and, somehow, the pulse of electricity would transfer IT’s essence into the Celtics. Because what the Celtics did in the fourth quarter Friday night was definitely worthy of Thomas tapping his wrist and waving his arms to the crowd.