9. A system comprising: a plurality of processors; a media module implemented by at least one of said plurality of processors that retrieves a requested media file from a media file database and streams the requested media file to a requesting rendering device, the requested media file requested by the requesting rendering device; and an advertisement selection module implemented by at least one of said plurality of processors that accesses at least one data source containing contextual information describing portions of the requested media file, selects a different advertisement for each of at least two different portions of the requested media file based on the contextual information describing the at least two different portions, and transmits the different advertisements to the requesting rendering device.
12. The system of claim 9 wherein the at least one data source includes: a metadata database containing keywords describing different portions of the media file.