Multiple rating versions of content are provided and selectable by a viewer. A user can select one of the rating versions of the content for viewing. The user selection is dynamic such that the user can change the rating version selected while watching the content. Substitution instructions and substitution segments are downloaded and stored in a substitution cache. When a substitution descriptor is encountered in the content, a processor obtains at least one substitution instruction that corresponds to a substitution instruction identification code stored in the substitution descriptor. The processor executes the instruction to effect the rating change.