Dynamically replaceable assets are inserted in program content and may be used for the insertion of cinematic stage props therein. Such assets can be used for advertising purposes in that images of different products and services can be inserted therein and are changeable via a network. Such assets may be created by identifying locations in the content where the assets can be inserted, establishing the assets in the identified locations, and determining location and visual effects information for each asset. Replacement images, such as images of products, may be obtained via a network. The visual appearance of each replacement image may be modified using visual effects information so the inserted objects appear natural as if they were part of the original scene.