I'm trying to download the Clay Render Addon but everytime I click the link I get blasted with a Security Certificate Cannot Be Trusted. It happens on Chrome, Explorer, and Fire Fox.

When I press Proceed Anyway, All I get is a webpage with the clay render coding and no download.

Anyone know what the issue is?

I've just gone through the process and everything seems to be cool. I'm using Windows so the steps might be slightly different if you're using another OS.
Go to the webpage with the code.
Highlight all the text and copy it (CTRL C)
Open a simple text editor (Notepad on Windows) and paste in the copied text (CTRL V).
Save the new document into Blender's Addons folder as clay_render.py
Fire up Blender, look for Clay Render in User Preferences and away you go.