This technique seems to work better if more than one hummie vies for a sip. :)
Also, another tip, if the hummies seem to be relaxed with your presence around the feeders, it works better [perhaps a little later in the season?] I have a pair that have been coming for years, *Squeakie* and *Mrs. Squeakie*; the male squeaks at me when he comes to the feeder, a very social little guy. *Mrs.* showed me her tongue.
Only once was I lucky enough to observe their mating display, a *J* like fly-dipping. Very cute [like this]: http://www.bing.com/videos/search?q=ruby+throated+hummingbird+mating+display&&view=detail&mid=F9EB11D36A75AA4CE51FF9EB11D36A75AA4CE51F&rvsmid=F9EB11D36A75AA4CE51FF9EB11D36A75AA4CE51F&fsscr=0&FORM=VDMCNL