Wikipedia:List of online video archives

YouTube by Google
Fox Movietone by Fox Studios from 1928-1963 in the United States, and from 1929-1979 in the United Kingdom, archived at University of South Carolina http://www.sc.edu/library/mirc/ and ABC News for the United Kingdom footage
The March of Time by Time-Life from 1935 to 1951 http://www.thoughtequity.com/video/home.do?forward=mot
Universal Newsreel by Universal Studios from 1929 to 1967
Hearst Metrotone News (renamed News of the Day in 1936) newsreel series produced by Hearst Corporation from 1914 to 1967 was distributed by Fox Film Corporation 1929-1934 and by MGM 1934-1967, archived at the UCLA Film and Television Archive and Packard Humanities Institute
Paramount News newsreel series produced by Paramount Pictures from 1927 to 1957
PathÃÂ© News newsreel series produced by PathÃÂ© Film from 1910 to 1956 and later distributed by RKO Radio Pictures 1931-1947 and then Warner Brothers 1947-1956