News video of them. They were arrested. http://www.nbcwashington.com/news/local/Capitol-Police-Arrest-Protesters-Inside-Senate-Office-Building-131525243.html
Since when is having a banner illegal?
I hate paid by union unwashed commies as much as the next guy, but I am all for Americans flooding DC and shutting them down. Last I checked those buildings were owned by American citizens.