Did you know that harmonica groups were a HUGE phenomenon in the USA, prior to WWII?
They tended to consist of:
1️. A bass harmonica player covering the bass parts
2. A chordal player playing a special instrument that had all the chords needed
3️. A lead player, who’d usually play a chromatic harmonica.
The first harmonica group to gain national fame was created and promoted by Borrah Minevitch called the Harmonica Rascals. There was a lot of slapstick and showmanship involved in these performances, but also a lot of virtuosity.
But what do you do if you want to do a harmonica cover of Mr. Sandman by the Chordettes and there’s only one of you? 
You use the magic of technology, which is exactly what Alex has done to create this[ one-man-band performance of Mr. Sandman.
Since bass harmonicas are hard to come by these days, and computers are ubiquitous, Alex cleverly played the bass part on a regular harmonica and pitched it down on the computer. Ah, the miracles of modern technology.
Alex even added in some record hiss and “lo-fi effects.” Isn’t it ironic that in the days of pristine digital audio we now purposefully “dirty it up” to give it that old analog nostalgia?