I have never seen that message when I visit speedtest.net.
Why is that? Because I am using Firefox with the Adblock Plus Add-On. I don't see any pop ups ever. Think of what I am missing. I do see what you mean if I use IE or Chrome though.
Now Adblock Plus used to not work with Chrome, but now I see that it does so if you do not have it, why don't you get it?! In Chrome, you may need to visit Tools, Extensions, Adblock Plus, Options and update manually. I guess they need to work on that part... Then you will not see that message anymore or any more pop up ads (I just tried it).
To test, visit some WWW page you know has ads (like speedtest.net), disable Adblock Plus, then refresh the page... Ugh!
Dang... Now I have to come up with some enhanced instructions.