This is the “loading” of the classic ZX Spectrum computer game Manic Miner coded by programming genius Mathew Smith. The data is converted into audio and sold on cassette tapes. Instead of a disk drive, you would plug in an audio cassette tape player into the ZX Spectrum computer and “play” the sound into the computer, which would then read this audio as data and use it to load the game into memory, after which it could then be played. So instead of distributing the audio as cassette, in this case that same audio is broadcast over the radio and people would record it from the radio onto a cassette tape. Then playing the cassette into the computer would load (“download”) the game into the machine. Primitive but it works, and what we had to put up with.
Imagine being six years old and wanting to play Manic Miner, and having to sit there for 6 minutes while your TV did this before you could play the game:
https://youtu.be/kHn_BvTBALI?si=5CrKYa6DlNZTN7In
(Please watch in full without doing anything else or scrolling for the authentic experience)