When a hearing person asks you "Why should I support closed captioning online? I'm not deaf!" this is what you can tell them: closed captions online are like curb cuts.
What is the similarity here? Curb cuts are mandated by law to help disabled people. We are all only temporarily abled. You never know when you might need something that was put into place to help.
For example, years ago Robert could walk and even run. Today, he needs a wheelchair or cane part of the time and will never be able to run again. He developed arthritis and entered the world of the severely disabled. On December 2008, he had surgery due to his bad knee condition. He's talked about it on his blog, RSGeo-007.
If curb cuts were not in place, he would not be able to get around independently in a wheelchair. Likewise, if a hearing person were to lose hearing either to age, illness, or accident they would be unable to watch television online just when they need to be able to. For example, think of an office with no television but only a computer at a time of hot news on television.
Ask the hearing person, "I know you don't need captions now, but someday you might need them. Wouldn't you want that in place already, ready for you if you needed it?"
Write to your representatives and join Caption Action 2!