Conure beak-clicking? Aggression, protectiveness, or unhappiness?

So Loki, my YSGCC has a special sound he makes when I walk too close to his play-stand or get my hands too close for him. I jest and call him a rattlesnake, as usually you'll hear the clicking before he goes to bite, the silly little guy.
I know I'm not his favourite(He prefers Brad, Kiwi prefers me. It just sort of happened that way.) but if he's on his cage or stand, he won't step up, he'd rather take a chunk of skin.
(I'm being dramatic- he has pressure bites- very rarely draws blood, just bruises.)

If he's anywhere else, on my chair, the TV, the bed, he'll bite if I try to pet him.. but he steps up. And once he's on my hand it's a guessing game. Sometimes he'll let me pet him, and sometimes he'll realize it's me and attack the hand he's standing on!
He's fine with everyone but me(once he's off his cage.) He lets strangers hold him and pet him, he's not really mean.

Rambling now. I love him as-is, he still likes my attention and we have a love-hate bond. I have no issues caring for him fully, he just likes Brad's attention more.
My real question is the clicking sound. Does anyone else have a GCC(Or conure at all) who does this?

It's a short video, and I know it sounds like something is tapping on the camera, but it's coming from Loki the way he clicks his beak. He doesn't chew on anything when he does it, it's just something he started doing in the past couple months.

[ame=http://youtu.be/8TQvRKvsrV4]Mar 27, 2014 - YouTube[/ame]

I watched your video. One of my conures does the same. He sounds alot like the way you described your bird (moody, protective, choosey and at times bitey). Even the body language your Loki has in the video - reminds me of my ChiChi. I have no proof, and may be wrong.. but have chalked that certain clicking to be a warning to all the above in your title.

Does he do the clicky sound to your partner, his chosen human lol?
Does he bite your partner at all?