• by Mark Walsh  @markfwal, December 22, 2008

Online video network YuMe saw a steep decline in its ranking in the latest Ad Focus report from comScore. YuMe dropped from the 14th- largest ad network in October with a potential reach of 130.2 million, or 68% of U.S. Internet users, to 43rd--at 50.8 million, or 27%, in November.

A comScore spokesperson said the large traffic drop-off resulted from YuMe having a "revised traffic partnership" with Microsoft that limited its reach to MSN's video channel. Molly Gallatin, marketing director for YuMe, however, said the company's relationship with Microsoft has not changed.

Rather, YuMe hadn't provided new paperwork required by comScore to validate the full extent of its ad partnership with Microsoft by the November reporting deadline. Only its potential reach on the MSN video channel had been verified by then.

YuMe raised eyebrows last summer when it shot up into the top 10 ad networks via a deal to sell remnant video inventory on Microsoft Web properties. Since August, comScore has distinguished between potential and actual audience reach in its Ad Focus rankings.

So, the 173 million unique visitors and 91% reach of AOL's Platform-A--the No. 1 ranked ad network--reflects the total number of Web users that actually saw its ads. YuMe's potential reach simply reflects the total traffic of the sites for which it has video ad agreements.

Gallatin said she expects the company's comScore numbers to go back up once Microsoft completes the legal paperwork confirming all of the company's Web properties partnering with YuMe.