I have a popcorn machine that produces popcorn without using fat. It basically blows hot air over the kernels, and after 2 minutes they start popping.  You're not supposed to add any flavoring agent (salt, sugar, ...) in the machines as it's not made for that. So when I want to add flavor, I spray water onto the popcorn right after it has popped, and then scatter the flavoring agent. This works relatively well.  The downside:    the popcorn can become damp (I solve this by leaving the machine on, which blows hot air over the popcorn) you can waste some flavoring agent (not all of it sticks to the popcorn, some of it falls on the bottom of the bowl)   The upside:   no fat used, healthier and your fingers will be less "greasy"   Any other ideas how to flavor your popcorn using no fat or a minimal amount of fat? 
While movie theaters do often add flavoring agents (e.g. Flavacol) during cooking, that's not all they do for seasoning— they also use popcorn salt which is simply extremely finely ground plain salt. Morton, among other salt companies, package it for sale in grocery stores. It sticks perfectly to popcorn with absolutely no liquid or fat whatsoever. If you can't find any, and don't feel like ordering it online for some reason, putting salt into a high speed blender, spice grinder, mortar and pestle, or some other grinding device does the trick.   For a sweeter corn, you can use a shake of confectioners sugar. It would be great with a shake of cinnamon.  I love to add a touch of garlic powder and a shake of smoked paprika to mine! My wife absolutely swears by brewers yeast for her popcorn... she even brings a little jar of it with her to the movie theater.  Good luck and happy popping! 