Try moving real slow, stay back and zoom in. If you have you camera right next to the cham maybe it can see itself in the lens?? Causing it to puff up.
Glad to hear your cham is doing good. When i first started reading i thought maybe your cham burned his tongue on the light fixture somehow. The shiny glare could attract a cham. This could be part of the attitude and why its drinking so much. Also, didnt you say its tongue was discolored? NOT...
I would not recomend doing this. Chameleons need live insects for their neuroscience. Also, i think canned bugs would not offer as much H2O for your cham.
BUT this dish may be a good idea for those who cant get their roaches to move enough to get their chams attention. :)