Not that any of us can hope to equal the sublime genius of This American Life, but I think that, for your three stories to constitute authentic practice, you have to go beyond the talking-head approach. You have to incorporate interesting visual elements, or music, or something.

Also, TAL comes off as very informal, with ums, ers, and other elements of off-the-cuff monologues. But you can bet that Ira Glass and company have edited and re-edited these to an insane degree. So I think the ideal is to seem artless while putting a great deal of time into the production, the delivery of the story. That kind of investment, I would guess, would also be part of authentic practice.

Bravo that you posted these practice stories. That’s awesome. And yes, I agree with the poster above who notes how much academic librarians can learn in the way of storytelling from, say, a children’s librarian, who pretty much tells stories for a living.