I'm interested to how this applies to Reactive application-UI programming (e.g. React+Flux).

React has a powerful unidirectional data->UI flow model, but I haven't seen an expressive language for the other awy (putback functions), besides UPDATE statements in various db query language, but I figure there's gotta be more symmetry between the languages expressing data->UI and UI->data.

Is there a video of this talk?

Take a look at Boomerang programming language: https://alliance.seas.upenn.edu/~harmony/ and its documentation, they have a bit of explanation of lenses there. Also, on the frontend/in JS we also have some implementations of lenses, most notably in Bilby.js: http://bilby.brianmckenna.org/#lenses

Unfortunately I've never found a video of the talk.

A quick Google search revealed the paper "Reactive Lenses" [1], which seems relevant. I haven't read it yet, but the abstract seems promising.

Edit: It looks like the paper has more to do with Functional Reactive Programming than Reactive. There's still some interesting ideas in there though, and it'd be interesting to implement them for something like Elm.

[1] http://soft.vub.ac.be/REM13/papers/rem20130_submission_10.pd...

Looks like it's closely related to homomorphic encryption.

Any ideas on what was used to author the presentation ? Powerpoint ?

It looks like it was made with Beamer, a package for LaTeX for making presentations: https://www.sharelatex.com/learn/Beamer. It's pretty popular in mathematics, physics, and computer sciene theory.

Impressed by the animation in the figures.