That's maglev technology that you see them using. Maglevs use electromagnets to levitate above the track and achieve high speeds.

The London Underground could really use some air conditioning both in stations and on trains. The proper solution to the problem I think would be to build more ventilation shafts to let out hot air. One of my favorite Youtube channels is Jago Hazzard, a Youtuber who makes short little videos about London trains. He's made a video on hot underground trains before.

I did know of the Soviet traveling film trains, they are cool as hell. Bring back doing literally everything with trains.