Nielson online has announced its rankings for the top video streaming sites online. YouTube has held onto the top spot with 5.5 billion videos streamed in April. However, YouTube may find one day that it is no longer the top video streaming site. Hulu is coming on very strong, no doubt helped by the big marketing push that sees commercials for the site on TV frequently.

Hulu increased its video streams by a massive 490% year-over-year growing from 63.2 million streams in April 2008 to 373.3 million in April 2009. That marks Hulu as the fastest growing brand in the top ten video sites.

The number three spot went to Yahoo with 203.6 million streams with Fox interactive Media in fourth streaming 201.3 million videos. The largest growing demographic in online video watching is the 35-49 group spending the most time watching video of any user group.

Via Nielson Online