Fasten Your Hamster's Mask First

The unnecessary safety video preceding every flight I'm on cautions me:

Remember to fasten your own mask before helping others.

Why? I can't imagine a scenario in which the person you're inclined to help is more capable than you in terms of dealing with sudden low pressure.

Succumbing to boredom I glanced at the printed list of exit row passenger exclusions. Number 11 is my favorite:

Traveling with an emotional support animal, service animal or family pet.

First, I applaud their non-use of the terminal comma there, but what exactly is an emotional support animal? Can I travel with a hamster if I can get a doctor to sign off on my emotional need of its companionship? I wonder if they'd let him ride in my shirt pocket. If I were taking a hamster on a plane I'd definitely wear a shirt with a pocket.