They seem to use a script to pop the link up whenever there's an interruption in playback. It doesn't always show up.
I'm not really sure I buy their implied assertion that it's the ISP and not their servers that are causing the issues. Not that I think Centurylink has my best interests in mind, but I don't have nearly as many issues with any other video streaming site.
It's really conservative. My ISP is also rated at "standard definition" but when I go full screen on youtube it always jumps to 1080p after a couple seconds.
And clicking on the "compare providers in your area" button, it also says that Xfinity by Comcast is HD verified. Yet part of why I left Comcast was YouTube (and the other part being Netflix) couldn't handle HD during prime time.
I have to think it has no idea what's going on in my area.
I do not understand what I do. For what I want to do, I do not do. But what I hate, I do.