I agree, I don't see how people can believe this will really work.
First off...if we do get attacked and biological weapons are used it wont be in the form of a missile. It will be in the products we use daily like soap, lotion, shampoo, and in our food and water. It will come from the "sleepers" that are already in this country. You wont know you have it till its to late so what good will duct tape and plastic do.
Second...How are these people planing to seal off their chimney. I don't know where they live but where I live there is about 3 foot of snow on the ground. IT'S COLD OUTSIDE.
Just my opinion.