A method of substitution of digital video content at a content player device, comprising: receiving a segment of video content having substitutable portions, the segment of video content being encoded using a first video encoding method; identifying a fixed segment of the segment of video content using a first segment identifier; receiving a plurality of sets of substitute segments (354, 356, 358 360) of video content which are identified by a corresponding plurality of segment identifiers; wherein the plurality of sets of substitute segments of video content are encoded using a second encoding method, wherein the second encoding method produces more highly compressed video content than the first encoding method; determining that one of the plurality of segment identifiers corresponds to the set of substitute segments of video content that is to be substituted by reference to a look-up table stored in a memory device, the look-up table identifying the one of the plurality of segment identifiers; determining that the segment of video content contains the one of the plurality of segment identifiers; inserting, at a substitution point in the segment of video content, the set of substitute segments of video content having the one of the plurality of segment identifiers and disregarding the sets of substitute segments of video content not identified by the one of the plurality of segment identifiers, wherein the substitution point is determined by a time or segment counter of a first segment of the set of substitute segments of video content having the one of the plurality of segment identifiers; and during playback of the segment of video content, in an insertion/deletion mode, upon encountering the substitution point in the segment of video content, switching from a first decoder that decodes the segment of video content encoded using the first encoding method to a second decoder that decodes the inserted set of substitute segments of video content encoded using the second encoding method, and upon completion of decoding the inserted set of substitute segments of video content, switching from the second decoder back to the first decoder. receiving a segment of video content having substitutable portions, the segment of video content being encoded using a first video encoding method; identifying a fixed segment of the segment of video content using a first segment identifier; receiving a plurality of sets of substitute segments (354, 356, 358 360) of video content which are identified by a corresponding plurality of segment identifiers; wherein the plurality of sets of substitute segments of video content are encoded using a second encoding method, wherein the second encoding method produces more highly compressed video content than the first encoding method; determining that one of the plurality of segment identifiers corresponds to the set of substitute segments of video content that is to be substituted by reference to a look-up table stored in a memory device, the look-up table identifying the one of the plurality of segment identifiers; determining that the segment of video content contains the one of the plurality of segment identifiers; inserting, at a substitution point in the segment of video content, the set of substitute segments of video content having the one of the plurality of segment identifiers and disregarding the sets of substitute segments of video content not identified by the one of the plurality of segment identifiers, wherein the substitution point is determined by a time or segment counter of a first segment of the set of substitute segments of video content having the one of the plurality of segment identifiers; and during playback of the segment of video content, in an insertion/deletion mode, upon encountering the substitution point in the segment of video content, switching from a first decoder that decodes the segment of video content encoded using the first encoding method to a second decoder that decodes the inserted set of substitute segments of video content encoded using the second encoding method, and upon completion of decoding the inserted set of substitute segments of video content, switching from the second decoder back to the first decoder.