Looks like Google had to rush through to release the Priority Inbox feature to users because of a broken embargo. The release faced a small glitch where a automatic YouTube video started playing when a user loaded Gmail, apparently only in Google Chrome.
This is happening to users for whom Priority Inbox has been enabled for. Here is what the problem users are (or were) facing:
Whenever I sign into my Gmail using Chrome, music automatically starts playing. This is a new issue. It’s like old time dance music. Occasionally there will be a sound effect like a click, a bubble, cards shuffling, a dog growling. There is no music running on my computer. It only occurs in Google Chrome on one of my Gmail accounts, it does not occur in Firefox on anything.
And what was causing it? Apparently this:
Hey, I figured it out. Weirdly, that little "New! Priority Inbox (Beta)" automatically starts playing a youtube video that you can’t see. when you click on it you’ll see that.
It looks like Google employees are aware of this issue are working on a fix as per this thread on Google support forums and the suggested fix is to use Firefox for time being (Hotmail Part Deux?). Nevertheless, looks like Google panicked because of the broken embargo by eWeek and rolled out a code with an auto-play YouTube video. Nothing major, but goes to show that even the biggest company can make mistakes in haste.