There was a huge protest march in San Francisco Friday evening. Unfortunately I couldn't get away from work to take part, but the silver lining on that cloud was that at 10 PM as part of my job I drove a highly placed SF city official to SFO and while doing so was able to learn the official estimate of the crowd size. The SFPD no longer releases these numbers to the public, but my passenger told me that the SFPD estimate given to City Hall was that 20,000 people were involved at the peak of the march.
There is really great video HERE. I tried embedding the video, but it self starts, which is tacky, so please click on the link. There is more video here: http://www.ktvu.com/video/17936851/index.html