There are lots of sites like these, I don't believe that any of them take effect. People still could post success stories etc. I have yet to see it, you can try them.
That looks like a web version of the Poor Man's Copyright where you mail a copy of the work to yourself. The U.S. Copyright Office's website spefically states the copyright law does not give you this kind of protection. If you want to protect your work in a court of law you need to have it registered with the U.S. Copyright office. No makeshift copyright will work.
This is something you need to cover your bases on. Read the copyright office's website regarding how to file, but also speak to a qualified attorney in your area. Many consult for free, and even if they don't, isn't $100 or $200 a small price to pay for peace of mind that if your content is ripped off, you have a legal recourse? Just a thought. Thought I'd chime in, as at least I had something intelligent to say about the subject (unlike some of the other threads! LOL) Have a nice day.