The offline CHM is great for fast offline access and best of all, it's just Silverlight docs. You won't get any other technologies mixed up in your search results, index, etc.
The purpose of output protection is to increase content protection during transmission between a computer’s video or audio output port and the input port of another device such as a monitor or set of speakers (output). This is useful to prevent someone from intercepting copy protected content “en route” between such devices, known commonly as an "analog hole".