Indeed, MJH played many guitars during his short career: Tom Hoskins' Emory slothead that he let MJH borrow, a "no name" guitar that was personally made for him by Jack Alderson who lived southwest of Philadelphia near Chester at the time he made it (that guitar was still in MJH's home when I last visited in 1968), Stefan Grossman's guitar, and many others that he borrowed at the coffeehouses where he worked, ack Aldersonincluding a 12 String.
That very guitar that you see him playing on Rainbow Quest was in MJH's home, when I was there last in April of 1968. The strings were so rusty until I had to put on new strings to make it playable. The abrasion may not be noticeable, but it was there. I kid you not, my friend. Do you see that white rectangular spot on the bottom fret? That was an engraving of his name, "Mississippi John Hurt". Around 1964, MJH showed it to me, when he laid this guitar across my bed.
I noticed recently that it is the same way Mark Knopfler plays guitar by the way. Always the little finger/ring finger on the pickguard anchored. It's amazing what he can play with just thumb and two fingers!Interesting how Hurt anchors with two fingers and only plays the 3 note alternating bass here and there. Mostly he's alternating two strings.