Google video now has streams of some National Archive footage.
This excites me. Especially when I find stuff like...
WHO'S OUT THERE?, a half-hour film about extraterrestrial life narrated in part by a bloated, histrionic Orson Welles...
and CHILDREN OF THE CITY, which features a remarkably bad folk-rock title song "Think of all the kids without a tree...all that ever grows for them is buildings..."
Here's a link to the complete list of NARA films available at Google. HAVE FUN!