Lightroom 4.1 Help help
Check the box that says "This reference only"
On my LR4, this box says "Adobe reference only" and restricts the help topics found, to just the Adobe web domain instead of the wider Web.
Either kind of search is made based on the particular product selected in a dropdown.
The problem here is: when LR4 is for some reason not listed in this dropdown, you cannot make your help search specific to that; and will in fact exclude rather than include the results you are looking for.
There is also a current thread on this in the Adobe LR forum.