So, I wrote a document in LaTeX. Someone who doesn't know LaTeX and is a very busy person now has to edit it. Is there a crash course in LaTeX document? Aside from saying 'Ignore everything that starts with \'? Like a one page \textit means italic, % means a comment; you can ignore anything after this, type of thing? It is a really simple document, just straight text basically.
Share the LaTex over online editors like ShareLaTex. They highlight keywords and syntax and your friend will be able to clearly point out text he needs to review. If he wants, he can also look at the PDF preview.
To most people that are used to Word, OpenOffice or similar WYSISWG word processors the syntax of LaTeX will take some time to digest. Whereas I think it is worth the effort to learn if you want to typeset nice documents an "emergency case" might not be the right opportunity to start learning it. I personally cannot edit the LaTeX source from other people instantly but always have to spend a little while understanding their choices of packages and commands.
For pure editing it is often much easier to use the nice tools that are available in many PDF readers, such as Adobe Reader or Foxit to mark the corresponding parts of the document and let the author deal with incorporating the changes.
There is little benefit if you receive an non-working edited LaTeX file that you have to debug to even be able to use
latexdiff to see the changes.
Alternatively we discussed also the possibility to convert to a different format and back to LaTeX: Convert TeX to non-TeX and back.