I don't think that would help for what he is doing. If you were to click on his download link, you would notice the following fine print below the download button:

The key in that quote is "Adobe may use the Adobe Download manager to seamlessly install your software". What this is saying is that clicking the download button is not clicking a button to download Adobe Reader at all, but it's a button that installs a Firefox (or Internet Explorer I'm sure if that's what you're using, and maybe Chrome or Opera too?) add-on named Adobe Download Manager. Yes, the download manager that is installed is programmed to immediately download and install Adobe Reader, but it's still the download manager that you're installing to your browser by clicking that link.

The download manager isn't going to care where you store your Documents or Pictures folders. It's going to store the downloaded files as well as install them on the C drive, or whatever drive your operating system resides on.

Moving the Documents and Pictures to your second hard drive or a different partition has many useful benefits. However, in this situation, it would not accomplish the desired effect.