[README.md] Clarify location for youtube-dl.exe

README.md

@@ -25,7 +25,7 @@ If you do not have curl, you can alternatively use a recent wget:
     sudo wget https://yt-dl.org/downloads/latest/youtube-dl -O /usr/local/bin/youtube-dl
     sudo chmod a+rx /usr/local/bin/youtube-dl
 
-Windows users can [download a .exe file](https://yt-dl.org/latest/youtube-dl.exe) and place it in their home directory or any other location on their [PATH](http://en.wikipedia.org/wiki/PATH_%28variable%29).
+Windows users can [download an .exe file](https://yt-dl.org/latest/youtube-dl.exe) and place it in their home directory (`%USERPROFILE%`, for example `C:\Users\<user name>\` or `C:\Documents and Settings\<user name>\`) or any other location on their [PATH](http://en.wikipedia.org/wiki/PATH_%28variable%29) except for `%SYSTEMROOT%\system32` (e.g. **do not** put in `C:\Windows\System32`).
 
 OS X users can install **youtube-dl** with [Homebrew](http://brew.sh/).