Thanks for the video. You seem to be screwing on more than I did, when putting the chuck on, and unscrewing less than I, when taking off.
P.S. I think there is one definite advantage to Jaco, in that it is quite compact in spite of being dual-valve. Some dual-valve chucks can be unsuitable for tight spaces.
Yeah, I screw the thing on probably too much. It seems to seal with just a few twists, but I tend to go until I feel some resistance. Same tendency probably affects the initial air leakage on a presta valve - I push the chuck on a bit too far before tightening. I'll have to try it a bit less aggressively.
All in all, I think I can say that I like this chuck. I bought it specifically because I can use it with the inflator that I've been using on my car tires, but after some additional thought prompted by the discussion in this thread, I think I might have liked a different system better. In any case, I'm glad that I was able to offer this review to the forum community.