In short, Google and YouTube came under a lot of pressure for not doing enough to stop those who upload copyrighted materials. This tool is part of Google's solution to that problem. But will it work?
I am sure there will be many piracy advocate groups who come out and test the new tool. Give it about two weeks until those reports come out. Until then, the folks over at WebmasterWorld are very skeptical.
Forum discussion at WebmasterWorld.