The editing tool, until now only available in countries where Google was actively looking for crowdsourced data (that is, less mapped ones) is now available for editing Google's own U.S. dataset. It's only available in the browser for now, but it's likely a mobile implementation will appear. The tool includes access to StreetView data (to check your edits I guess) and a granular search engine. Edits are reviewed by a Google team and can go live quickly (we'll see how quickly); your history as an editor has an impact on that speed. As TechCrunch notes, far more people read about the availability of Map Maker in the U.S. than will actually use it.
The video is basically an ad.