Each of these stationary pictures is made up of more than 500 lines of light called "scan lines. Each scanning line is also made up of a great many points of light.
In other words, a TV screen is made up of hundreds of thousands of dots of light.
Each of these dots of light is converted into an electrical signal and recorded on tape, which is what video tape is. However, the number of electrical signals is incredibly large because the screen sends 30 signals per second.
These huge electrical signals are recorded on a "magnetic material" that is coated on the tape.
The magnetic material is simply called a magnet. The surface of the tape is coated with a magnet as fine as 1/10,000 of a millimeter, with no gaps in between.
The dots of light that make up the TV screen are converted into electrical signals that arrive at a place called the recording head. A tape runs in front of the recording head, where the electrical signals are converted into the N and S information of the tiny magnets and recorded on the tape.
Television sound is recorded in a similar way. When you watch a video, a playback head reads the signals recorded on the magnetic material and converts them into pictures and sound.