After years of hoarding its original video content on its own sites, Disney is suddenly branching out in a major way.

Early last month, the ABC/ESPN parent company signed a deal with YouTube. Now, as had been long rumored, ABC Enterprises is becoming a partner in the video site Hulu, which was launched last year by NBC Universal and News Corp.

The deal will allow Hulu to post full episodes of such popular ABC shows as “Lost,” “Desperate Housewives” and “Grey’s Anatomy,” as well as ABC Family fare like “The Secret Life of the American Teenager” and “Greek.”

The move was prompted by ABC’s desire to reach out to online video viewers beyond the so-called core fans who come to its site specifically to find one or two shows they may have missed on television.

ABC programs had thrived on that model, with the network the first to make its shows available online several years ago. But since then, online video viewing has exploded, and Hulu in particular has seen huge growth since last year’s launch, vaulting to the No. 3 video site on the web, behind only YouTube and Fox Interactive Media.

The deal Disney struck with YouTube provides only short clips from its shows. The Hulu deal includes current shows and so-called classics like “Who Wants to be a Millionaire,” as well as some episode recaps.

Disney CEO Robert Iger will take a seat on the Hulu board.

The deal means that CBS is now the only Big Four network without a Hulu presence. The network does have some 300 video distribution partners online, however, and has reportedly turned down previous Hulu overtures.