offer a sampling of HBO's programming for potential subscribers of the service. Cable providers were given permission to offer the unscrambled HBO content—aired for a single evening or, beginning in 1981 at the network level (as early as 1978 on some providers), over a two-day weekend (later extended to three days in 1997, then to a Friday-to-Monday "four-day weekend" format by 2008)—over a local origination channel, though satellite and digital cable providers elected instead to unencrypt the channels corresponding to each HBO feed for the preview period. Until 2002, interstitials hosted by on-air presenters (notably including, among others, Norm Crosby, Greg Kinnear, Sinbad and Ellen DeGeneres) promoting the service and its upcoming programs to prospective subscribers aired alongside on-air promotions between programs during the preview weekend, although interstitials produced in-house or by third-party producers were inserted by some providers over the HBO feed during promo breaks for their local or regional audience; from September 1988 to September 1994, the network also aired a 15-minute-long promotional "free preview show" each night of the preview event—usually following the headlining prime time film—that previewed upcoming HBO programming for prospective and existing subscribers. HBO offers between three and five preview events each year—normally scheduled to coincide with the premiere of a new or returning original series, and in the past, a high-profile special or feature film—to pay television providers for distribution on a voluntary participation basis. (The total of participating providers that elected to offer a free preview event varies depending on the given preview period, and participating multiple-system cable operators may elect to carry the event only in certain regions where they provide service.) HBO also produces short segments promoting newer movies with the cooperation of the film studios that hold distribution rights to the projects (almost universally by studios maintaining exclusive pay television contracts with HBO and Cinemax, and which have been rebroadcast on the former during a film's pay-cable distribution window), and have usually consisted of either interstitial "behind-the-scenes" and interview segments on an upcoming/recent theatrical release or red carpet coverage. Currently, these segments air under the HBO First Look series of 15-to-20-minute-long documentary-style interstitial specials, which debuted in 1992 and has no set airing schedule. (Since 2010, the "making of" specials, for which HBO officially no longer uses the First Look name, are only identified under the banner for program listing identification.) The network previously produced three-to-five-minute-long feature segments that