L.A.-based Revver is a video-sharing site that's backed by some big-time venture money. Microsoft execs toured Revver's offices last month, according to CNET News.com, perhaps looking at a way to enhance their own video site, Soapbox, which recently went live. Revver's biggest calling card is embedding ads in video files and tracking how and when the ads are watched. Obviously, a lot of media companies would be interested in that technology, though the site is not drawing big numbers. And a couple of months ago, Revver lost its chief technology officer and two of its three co-founders. "Revver had better be thinking about one of two things. They either better find an exit strategy or a business model that makes money," Josh Martin, a Yankee Group analyst told CNET. One source said a deal wasn't imminent, but Microsoft's interest would indicate that it's looking for ways to one-up YouTube, which is owned by Google.