Hulu, the video site backed by NBC and News Corp, officially opened to the public on Wednesday following a closed beta testing period which began in October.

Hulu will allow users to view clips and full-length episodes of TV shows and movies. The videos are free, but users will have to sit through advertisements in order to watch the shows and films.

The site will launch with roughly 250 shows and about 100 feature-length films from the two studios. The site also expects to add new content in the future, when Warner Bros and Lion's Gate come onboard.

Jason Kilar, chief executive at Hulu, said: "With full-length episodes of current and archived television shows, feature films, sports and news, we believe Hulu is a step forward in giving consumers entertainment on their terms. "

Hulu is the latest attempt by television and film studios to build a money-making legal video site to rival YouTube. The studios have long been at odds with YouTube over the site's inability to prevent users posting copyrighted videos.

NBC and News Corp began work on the Hulu service last summer. The two companies hope that the effort will spread beyond NBC and News Corp, and bring new consumers and studios onto the site.

"Hulu's impressive content line up and user experience are equally important in bringing consumers back again and again," said Jeff Zucker, president and chief executive at NBC Universal.

"These are the same attributes that make Hulu attractive to major brands. Both groups see the value in a quality, clutter-free online service."