I think I may have caught one of the audio ads. This "Don't Miss" thing seems to be appearing when the audio happens - today I heard two overlapping audio bursts and noticed the page I was on had two of the "Don't Miss" video ads.

These were also the only two ads on that page that did not have the blue AdChoices triangle that allows you to report the ad back to google...so I"m not sure where they're coming from.