Apparently, this is the very moment when the rocket was first refueled.
SpaceX demonstrated the process of checking the Starship launch vehicle before launch. Now SpaceX is testing the third Starship prototype: both stages have already been delivered to the spaceport and installed.
Apparently, the video was recorded during a test refueling of the rocket. The white clouds in the frame are not smoke: liquid oxygen, which has an extremely low temperature, is used as one of the components of rocket fuel.
SpaceX expects the third Starship prototype to take off on March 14. The two previous launches were partially successful: the rockets took off, but in the end they certainly exploded.
During the third flight, the company intends to accomplish several tasks. The plan is to restart Starship's engines in space, transfer fuel between internal tanks, and open the payload bay.
If the flight is successful, the second stage of Starship will fall into the Indian Ocean. A soft landing of the stage is not planned.
This is interesting