OR, maybe it was just one of those scenarios where budget out-weighs common ******* sense. Well, that is if you're a Predator fan. The fact that the "Nolan" character can even use, or understand, Predator technology is an insult. Durp-eh-durp this button does this and this button does this.

Ha-Ha-Ha-ha, it's just a movie.
But really, do you think that the Predator species would not be able to see each other when cloaked? The cloaking device bends light making the creature INVISIBLE to us. Frankly, I had a hard-ass time seeing the cloaked Predator in the clips, and that was cool. But as far as that is concerned, it only bends beams of light, and doesn't actually camouflage heat. That's just me though, seeing as how I've seen ALL of the movies involving a Predator.