A pro-abort chain (protest)

I just happened upon this post about a pro-abort rally in Boston Click on it. Then click on the video footage.

It was a pretty meager rally for such a liberal area (maybe they don't feel any threat?) But I thought it was a pretty quiet event. Usually you picture pro-aborts as loud and attention-grabbing. I could have mistaken it for a pro-abort Chain (as opposed to a Life Chain?) Maybe they're borrowing that technique?

Anyhow, I just thought it was interesting.