That is not actual Sumo match but practice at their gym, or Sumo Beya. I personally think is not same as watching actual event. Anyway, my understanding is that during the tournament, such as OP’s situation where Tokyo Oo-Sumo Tournament is taking place, there usually is no early morning practice session at each Sumo Beya. Morning practice session take place at each Sumo Beya when there is no tournament. Visiting early morning practice at Sumo Beya is good option when tourists are in town when there is no Sumo tournament is going on.