That didn't work for me, so apparently I don't understand your instructions.
Here's what I did:

1. Navigated (with Nautilus 2.30.1) to a folder that has 120 issues of a
magazine, each issue in a pdf file.
2. Clicked one file, which opened it in Document Viewer 2.30.3.
3. Clicked the binoculars in the upper right part of Nautilus (there are no
binoculars in Document Viewer).
4. Entered my search term (Berwind) in the space provided, and pressed enter.
5. Nautilus reported, "0 items." Document Viewer didn't do anything.

In that directory, there are 6 documents (pdf), with 28 appearances of "Berwind"
(as reported by Adobe Reader in Win XP).

Have I misinterpreted your instructions (quoted below)?

(I am looking for a version of Adobe Reader for Ubuntu)