Netflix announced Tuesday morning that it reached agreements with CBS and Disney Channel to stream some of their most popular shows, which can be viewed on PCs or living-room TVs through new media-extender devices made by Roku, LG Electronics and Microsoft. The deals help to speed Netflix’s gradual transformation from a subscription-based movie-rental service that relied exclusively on the shipping of physical DVDs to an online-content provider with a wide array of programming. For the networks, it gives them another digital-distribution channel as they extend their brands beyond Apple’s iTunes online store, the early leader in providing primetime shows through the Web and still the most popular paid-download service. Netflix already offers 12,000 choices members can watch instantly online. The CBS and Disney Channel deals bring popular shows from the current season, including CBS’ CSI, which can be instantly streamed at Netflix when the new season starts in October, and Disney’s Hannah Montana, available in November.