Governor Rick Perry commits two fundamental mistakes in this short speech - which a politician or any leader with his experience should never make.
At the very beginning of this clip, Perry rubs his nose. A nose rub belongs to a general class of nonverbal signs known as Manipulators, Adaptors or Pacifiers (MAPs). In descriptive terms, MAPs are self-touching behaviors and are highly consistent with anxiety. Moreover, while they are not sine qua non for deception, certain facial MAPs are more highly correlated with lying-associated anxiety. In short, if someone rubs their nose while making a statement or answering a question - it doesn't necessarily mean they are lying, but (depending on the other nonverbals, verbals and paralanguage exhibited) - your index of suspicion should be significantly increased when this body language is displayed. A speaker should NEVER touch their face. NEVER. Of course most audience members won't have any body language training - but this and many other nonverbal behaviors make them feel uneasy. This signal won't necessarily even register at a conscious level, but the candidate/speaker/CEO/salesperson, etc. will evoke feelings of suspicion and/or emotional discomfort in all who see them.
The second major mistake Governor Perry makes is his strong tendency to read from a script rather than making eye contact with the audience. The art of eye contact with an audience is a surprisingly scarce skill and is not as easy or straightforward as the words imply. Suffice it to say though, that in general, the less eye contact that is made by a speaker - the less he is liked, the less he is trusted, the less rapport is build - and thus he/she loses votes and leadership influence. I cannot overstress the importance of quality eye contact. A speaker/leader/candidate should know the issues well enough to talk in an educated and sincere fashion even if woken from a sound sleep.