The Library of American Broadcasting holds a wide-ranging collection of audio and video recordings, books, pamphlets, periodicals, personal collections, oral histories, photographs, scripts and vertical files devoted exclusively to the history of broadcasting.
Hulu is a free site that allows you to watch premium videos - TV shows, movies and web originals - online anytime you want. They have over 100 content partners, including Fox, ABC, NBC, the Food Network, HGTV, A&E, PBS, National Geographic, etc. You can watch these videos free of charge; in exchange for sitting through some commercials. [Info digested from Hulu web site]
This free access web site is "...an online exhibition presenting more than 300 television commercials from every election year since 1952, when the first campaign TV ads aired.... Each selected commercial is accompanied by a list of related ads. There is a transcript for each ad and a feature that allows visitors to search the entire database by title and by words in the transcripts." [from web site Guide/Help pages]