An interactive method includes receiving, at a display device, background
video including a multiplicity of video frames, at least one of the
multiplicity of video frames including a plurality of sub-pictures, each
of the plurality of sub-pictures representing an alternative background,
and switching, at the display device, between a first sub-picture of the
plurality of sub-pictures and a second sub-picture of the plurality of
sub-pictures. Related apparatus and methods are also disclosed.