Note that what this page is offering is not encryption because there is no decryption required in order for a browser to be able to execute the script. Instead we are just converting the script into a version less readable to visitors viewing the source and making the content of the script unrecognizable to web spiders.
Finally, let me remind you that these scripts do not stop people gaining access to your source. These processes just make it slightly more difficult for them to do so while at the same time perhaps encouraging people who otherwise would have no interest in your source to put in the effort to convert your source back into readable text simply because having encrypted/obscured it makes it look as if you think you have something worth stealing. This is particularly likely if you also try to interfere with the operation of their browser such as by disabling the context menu which draws attention to the fact that you don't want people looking at your source.
This article written by Stephen Chapman, Felgall Pty Ltd.