Before an animatronic is taken on set, they give it as much testing as possible. In the case of Polyphemus from Percy Jackson: Sea Monsters, they recorded their own in-house dialog from the script and pre-programmed the lip sync. By the time they shot, the script had changed. Much of the character's dialogue and action would not be settled on until post-production. The result is a heavily digital character. Here's their version. Courtesy of ADI.