I've been to tons of American conventions, and have never seen any such video, or heard any such announcement.
It plays at Dragon*Con every year, and has for at least the last five years. It's also in the program book for at least a half-dozen conventions I can think of off the top of my head.
Seriously? Wow...
I've only been to Creation Conventions. I never heard anything like that, nor had any problem with other convention attendees.
Creation wouldn't let bad hygiene get in the way of making a buck.
Both Creation and Hobbystar (their Canadian counterpart) could care less about that; that's why things like overcrowding and bad scheduling happen (in addition to the rough and rude treatment of people who line up for autographs and other nastiness that goes on at corporate-run cons like these.) None of this ever happened at the fan-run ones that I've been going to for most of my life, which should tell you something about those.