I've been doing that style thing for years and it's great. Have to say I disagree with his process a bit though. I don't have the space or time to let it carbonate for a few days.
I use a 1.5gal keg. Dump an inch or two of ice in the bottom and fill to about 1 gallon with water. My co2 regulator is set at 50psi. Connect co2 and shake for about a minute. You'll hear it stop bubbling. Leave connected on counter for 15 minutes. Light shake every time you feel like it for those minutes. Disconnect the co2 and put the keg in the fridge. Usually I leave it for another 30 minutes or so before having some.
No need to leave the co2 connected to serve with that pressure and space. You can be drinking the seltzer after that first minute if you want but it is better with that extra time. No patience for days.
... this is dangerous.
Of course, take appropriate precaution when handling anything that is under pressure.
Oh I meant for my consumption of seltzer!
