Right… But they aren’t operating in vacuum. Ships that large take a while to get any speed and lose it relatively quickly, they are moving a lot of water.

Ive since looked at the video, and it does clear things up a bit. Looks like they lost power and slowed, but when they regained power the engines were still engaged, causing them to pick up speed again.

Afterwards the power cut once again as they neared the bridge. When they came back on they threw the engines into reverse, which is what caused the bow to drift starboard