The video features the Beach Boys Shut Down Volume 2 pn cassette format.
The song playing is called Fun Fun Fun.
This cassette sounds great, but the video might not reveal the true sound quality because the Sony Walkman SS WM-20 speakers are good but they are passive with low bass response. The cassette is being played on my old Sony Walkman WM GX-674 which is a very cool Walkman. Sadly lost of my cassette players have stopped working and I can’t afford new ones, now that prices are going up.