I'm honestly not aware of any UI development platform that makes heavy use of functional techniques and immutable data outside of the web. Sure, papers have been written about the idea, but where else has it been used in practice?
RE: the video. I'm almost certain you know this, but Elm is a part of the web community.
(True Elm is part of the web-community, just saying React was not the first mover but I agree it will certainly be most likely the one that makes FRP cross the chasm)
However, I agree with above poster. I remember developing my first windows app by doing a main event loop. It's been that way for a long time. Only recently are we doing more asychronous callback / bound type mechanisms of reaction. And still not as strong as the FLP stuff mentioned in the video. Not as much functional stuff, just functional paradigms.
I personally really like the perfection of static input/output transformation graphs. But yeah..it's not been that way for a while and I agree with OP, the web being so event/input/signal based, has spurred the movement for better ways of reactive programming.
RE: the video. I'm almost certain you know this, but Elm is a part of the web community.