Instead of a tight-line hard-shooting water spray....pull the handle of your sprayer so lightly that it only drips. First, wait for your cham to be on a horizontal branch, so you can drip from above like they would do in nature when drinking from a dripping leaf. That's how they drink. I mentioned this earlier, but you can drip the water slowly on the front-middle of his casque and it should drip down towards his lips. They typically drink from below the water source, so try and match nature.
If you are really scared they aren't drinking enough, you can do this at feeding time after they finish chewing/swallowing their food. But again, I don't see you are having hydration problems....I really think from what you have shown us, there is nothing wrong with your cam drinking-wise. They might just need some more help getting water to a place they can drink from comfortably. Just what I'm seeing in the vid.