Archive.org TV news search
The Internet Archive now offers a free searchable database of over 400,000 recent television news broadcasts from major networks, organized into short video clips. (They also offer loans of DVDs by mail for a fee.)
TV news is often more difficult for researchers to search and locate what they need, so this looks like a great resource for researchers in journalism and related fields.
LexisNexis offers some searchable TV news transcripts, but not actual videos.