I've known people who can make that sound just by vibrating their lips pulled very tightly. I believe the pitch is generated essentially by humming (i.e.using the vocal chords) and I would imagine that it would take about as much practice as singing. You can hear how the range of his vocal effect is the same tenor range as his vocals. You could try a kazoo, but again creating good pitch requires practice like singing.
It might be good to remember that there was a time when you would have said, "I can't play banjo," and yet here you are playing banjo. Singing requires practice, too.
If you absolutely can't create melodic sound with your vocal chords you could try playing quills on a rack. Check the Tags index in the list of links under the top of page banner and find the tag links to all the topics about quills. Some in depth discussion here, as I recall. But, of course, that requires practice, too, but not as much as good harp playing.
Wax
