Abstract: A method for providing keys for descrambling scrambled content, the scrambled content being divided into frames, the method including: identifying a plurality of frames to be descrambled; for each frame of the plurality of frames, identifying a key period associated with a key for descrambling the frame; and for at least one frame f of the plurality of frames, substituting a substitute frame g for the frame f, the substitute frame g being chosen in order to reduce a total number of key periods associated with keys for descrambling all of the plurality of frames. Related apparatus and methods are also provided.

Abstract: Methods and apparatus for managing, implementing and using interactive applications and content that are digitally recorded and viewed in real-time and/or a time-shifted mode are provided. The interactive applications may be associated with television programs or may be unrelated thereto, and may be transmitted together with television programs or separately therefrom. Interactive applications that are employed in a time-shifted mode can be matched to current conditions and interactive content may be updated to include current data. Users may view and manipulate highlights of television programs and receive alerts of occurrence of real-time events during viewing of recorded material. Additional manipulations of interactive applications and content are also enabled. Related apparatus and methods are also described.

Abstract: A method for controlling access to content, including preventing access to content that corresponds to a blacked out event, until at least one of a time criterion and payment criterion is met. Related methods and apparatus are also disclosed.

Abstract: In a digital television recording method, programs are selected for recording based on analysis of program schedule information, user preferences, and the priority of previously recorded programs if there is insufficient memory.

Abstract: This invention discloses a method for displaying advertisements transmitted to a user unit, the method includes receiving, at the user unit, at least one advertisement tagged with a delay tag indicating whether display of the at least one advertisement can be delayed and only if the delay tag allows delaying display of the at least one advertisement, storing the at least one advertisement at the user unit, retrieving the at least one advertisement and displaying the at least one advertisement. A billing system for reporting a commercial broadcast to a multiplicity of users is also disclosed.