After lots of testing, the hit online video site Hulu has launched its Hulu Plus pay service for $7.99 a month.

The price is $2 less than originally planned and undercuts, by a dollar, the entry cost of Netflix, Hulu's biggest competitor in the market for streaming premium video content.

Since 2008, Hulu has streamed current and past TV shows and movies to PCs free, a service that in October drew nearly 30 million viewers who spent an average of 208 minutes on the site, according to comScore.

What differentiates Hulu Plus (www.hulu.com/plus) is the availability of full seasons of current TV shows, such as "Glee," "Modern Family" and "The Office," provided by the networks that started Hulu. It's offering more than 240 seasons of TV shows with 2,400 episodes.

The availability of network shows has made Hulu a useful service for consumers moving away from cable TV services, although the free version of Hulu might lose some of its appeal if the site moves more premium content behind its pay wall.

Hulu is taking its time with the Plus launch, though. For now the premium service will only be available on streaming media devices made by Roku and Sony's PlayStation 3 game console. The company said that covers more than 50 million devices in the United States. That does not include users who access the service on their Apple products or their home computers.

It's aiming to be as ubiquitous on Web-connected TV devices as Netflix. Hulu Plus will be available "in the months to come" on the Xbox 360, TiVo Premiere DVRs and Internet-connected TVs and Blu-ray players made by Vizio, LG and Panasonic.

Hulu Plus also is coming soon to Western Digital's WD TV Live Hub Media Center and WD TV Live Plus Network Media Player. Later, it's set to come to mobile phones, tablet computers and additional devices.

Hulu devices: For a list of devices supporting Hulu Plus, go to www.hulu.com/plus#devices.