I tend to focus on core concepts quite a bit more than actual examples, so that the fundamental understanding of what the examples are trying to teach me is building on skills I already have just haven't figured out how to use yet.
tl;dr Your mileage may vary. I learn kind of counterintuitively for others.
Presentations (40-70 minutes)
[SPJ talks about Lens] (https://skillsmatter.com/skillscasts/4251-lenses-compositional-data-access-and-manipulation) (Requires you to login, but is free to make an account)
This was one of the biggest influencers to me learning how lenses are supposed to operate.
[Creator Edward Kmett talks about Lenses, Folds, and Traversals] (https://www.youtube.com/watch?v=cefnmjtAolY&feature=youtu.be&hd=1)
[The Unreasonable Effectiveness of Lenses for Business Applications] (https://www.youtube.com/watch?v=T88TDS7L5DY)
Great talk about how the various components of lens are used. Highly recommend this talk once you have a basic understanding of how lenses are meant to work.
[Lens over tea] (http://artyom.me/lens-over-tea-1)
Shows about how to build lenses up from nothing and why they are useful to the everyday programmer. (I need to finish this myself. Damn ADD)
[From Lenses to Yoneda Embedding] (http://bartoszmilewski.com/2015/07/13/from-lenses-to-yoneda-embedding)
Talks about Comonads and how lenses fit into the whole big picture. Another one I really need to finish reading all the way through myself, but it does explain some (if not all) of the category theory behind lenses.
Not really meant to be an introductory material, but it does provide a neat reference with examples for how the most used infix functions of Lens.