Here is a list of useful resources, mainly files (pdfs) that can be downloaded and read offline. And some of them online.
The REAPER User Guide -- PDF file.
The essential guide to recording, editing and mixing with REAPER. For German, Polish and Spanish editions check REAPER's homepage.
GOM Player User Guide -- external link.
User guide for the well-known South Korean player, GOM Player. You can save the files into your Google Drive and download them later, on PC.
VLC user guide -- PDF file.
The complete user guide of popular media player, VLC.
DivX 10 User Guide -- PDF file.
Everything you need to know about latest version of DivX. See full list of DivX guides, here -- external link.
The Unofficial XviD FAQ -- zip file.
Almost all your basic and advanced questions are answered in this FAQ.
The Official DivX 5.2.1 User Guide -- exe file.
The Official DivX 5.2.1 User Guide is fully illustrated and in full color with step-by-step instructions and a Quick Start Guide.
YDY's English documentation for Media Player Classic (MPC) v1.0.84 -- zip file.
English help for one of the most powerful, configurable multimedia players, Media Player Classic (MPC).
Using DivX 6 with Virtual Dub -- zip file.
This Quick Start Guide will teach the basics of Virtual Dub and walk you through creating your very first DivX videos.
Dr. DivX User Guide -- external link.
This is the User Guide for the Dr. DivX software, specifically version 2.0.0 final.