It was basically a get-together arranged by YouTube to discuss online education - especially videos.
Loads of cool people were there, including quite a few who I'd met earlier this year at BrainSTEM and Vidcon... I won't bother listing them all again. You'll see some of them in the pictures below.
Excitingly, a bunch of them also gave me quick interviews for an upcoming Numberphile film. Stay tuned for that one!
While I was nearby, I also took the opportunity to visit Berkeley for periodicvideos because so many elements were created there. Videos from that are coming soon too.
In the meantime, here are some photos... And some links to secret "unlisted videos".
Coming in to land, the closest I got to the Golden Gate bridge!

Brady on the main stage (during a lunch break when everyone was gone!)
I did get to talk briefly during a panel - but here no-one seems to be looking at me! (video)
Better than stairs at YouTube head office (video)
Just chilling by the slide with Destin from Smarter Every Day (ladies form an orderly queue)
Yes there is a staff massage room at YouTube (video)
In the woods - from l-r (Vi Hart, Hank Green, Henry Reich, Derek Muller and me)
Vi Hart, Derek, Henry and Brady
CGP Grey spotted amongst the trees
Freaky picture of Henry in a tree
Hank Green and CGP Grey
At Berkeley there are car spaces reserved for Nobel Prize winners (not joking!)
The room where Plutonium was discovered
The sign on the room where Plutonium was discovered