• by Mark Walsh  @markfwal, May 14, 2010

Yahoo had better get that new ad blitz cranked up. New figures from Nielsen on Friday show the Web portal with month-to-month declines in traffic, time spent and video viewership in April.

Yahoo's overall U.S. traffic slipped 2.4% last month to almost 130 million unique visitors, while time spent per person on the site fell 1.6% to 2 hours, 24 minutes. To be fair, rivals such as Microsoft and AOL also saw declines in traffic and time spent, with AOL suffering a 6% audience drop to 80 million. That compares to a 4.5% gain for Facebook to 122.3 million.

Time spent on the burgeoning social network fell slightly by .3%, but at 6:43 this is more than triple the average spent on AOL, Google and Microsoft and almost triple that on Yahoo. In search, Yahoo and Microsoft held steady at 13.4% and 12.2%, respectively, in market share, while Google remained at 65.7%.

In video, an area where Yahoo has ramped up efforts lately, its audience fell 9.5% in April to 27.6 million. Gauging video viewership by total streams, Yahoo saw a 16.5% drop-off to 204,086. Fox Interactive Media, by contrast, enjoyed the biggest video audience growth last month, up 39.1% to 12.1 million.

The Wall Street Journal earlier this month reported on Yahoo's plans to spend $75 million to $85 million to launch a new ad campaign after its initial rebranding effort earlier this year failed to boost traffic to the home page. One video ad previewed takes aim at Google, showing an image of the company's site -- without its name -- while a voiceover says: "You come to this place so you can leave."

The 1:16 minutes spent per person on the Google home page in April is only about half that of Yahoo's 2:24, but still a respectable figure among top 10 sites other than Facebook. Interestingly, it's also more than its sister site, YouTube, where time spent was 1:06.

The close of the Yahoo ad also touts the site as No. 1 in categories like news, sports, finance and entertainment. Everything, it seems, except for total traffic -- where Google maintains a commanding lead at 158.5 million monthly.