Check out the video description for interesting links and stuff!
As for myself... I've not made any more flexagons yet beyond the four I have so far, but I've started a fifth one; and I finally did get some thinner paper, too. Attempts to find flimsy paper (yes, it's really called that) or bible paper were unsuccessful (and glassine would obviously not be suitable), but I found a store that has 50g/m² printer paper; they ordered a pack for me, and in the meantime, I picked up a pack of 65g/m² printer paper that they actually had in stock. It does feel thinner than the usual 80g/m² variety, too, and it'll be interesting to see how it will perform. I've got the pattern printed and cut out — I'll just have to glue it now.
And after that, I'll probably read up some on the background again, the mathematics behind them and all that. :)