This link is to DC Dept of transportation, seems to be very slow.
http://app.ddot.dc.gov/services_dsf/traffic_cameras/map_10.asp
This link is to Trafficland, which uses the DC Dept of transportation cameras, works better.
http://www.trafficland.com/findacam/trafficvideo.php?uid=0&map=19
For either map, click on the green dot on 7th Street, just above Const. Ave.
If video times out, just click on the dot again.
Good find! I'm watching it now, too.
Looks freezing cold. Just had a good cam on 7th and Independence - couldn't find Constitution. Now I have a cam on the Capitol Building. How exciting!