OCR (Optical Character Recognition) is a feature that can convert a scanned page (photo or image of a page) into a page with real text layer, so that you select text and it also becomes 'searchable'. If you open a PDF with scanned pages that are not yet OCR'ed, you can not select any text in it. When you zoom in onto the pages, you will probably see that they have been scanned. The text that you see will be of low(er) quality.
The example PDF that you sent, has been 'secured' against modifications, copying, ... by a password.
You can verify this in PDF-XChange Editor, when the PDF is open, via File > Document Properties > Security.
So, by consequence, it is not even possible to use OCR in it.
On the other hand, OCR that PDF has no sense, because it goes about real text. The origin of the content is not coming from a scanner.
An other thing that may be of interest to you, is that starting from the actual version 6.0 - Build 318.0 of PDF-XChange Editor, you can convert a PDF to a Word document (via File > Save As), on the condition that the PDF is not secured.