I hate to see that this will affect the good LPers and hobbyists who just want to share what they do with people who like Let's Plays. Myself, I've actually bought a few games I would have otherwise ignored because of them. But at least in the U.S., copyright and trademark laws are a pair of odd ducks. They were intended to help the small business owner, the artist, etc. They don't anymore, usually due to good lawyers finding legal loopholes in the language. That's the nature of the world we live in. Plus, laws based on internet content are still somewhat fuzzy as there are few rules around what constitutes theft or inappropriate use in digital media. That too will change in time. For now this is a draconian measure by a corporation that still has time to influence law because the law doesn't yet understand the medium.
Are there good LPers? Yes. Are there bad ones? Of course. Myself, I just ignore the ones I don't like. Should they all be shut down, the ones who make money and are successful at this, even do it as their job, will simply find another way to do this and make money without much interference. What bothers me is that we may lose people who really have something to add, or to say about the hobby they enjoy and the medium involved, or who are making art from games. As an artist and author myself, would I like to see someone ripping off my work directly, taking what I worked hard at to make money for themselves, or scrub my name from it and claim the work as theirs? Hell no. But that's not much what is happening here. Quite a number of the good LP's have much more: extra video production, good narrative, opinions, extra voice work, comedy, etc. It's a whole new medium to make art (video in this case), and guess what folks, all art doesn't just come from nowhere - it's built on the shoulders of those who created other forms of art (in this case, digital). I'd love to LP myself someday, when I have the money to massively upgrade my PC and get all the associated programs and goodies to do better quality shows, which I do not have right now. Why? Because I enjoy gaming as a hobby and I see much artistic potential with the Let's Play. I'm sure there are others who also see it this way and will be harmed. Others still who couldn't are less I'm sure, but oh well. It's too bad really, such potential wasted. And Youtube is still the biggest site on the web for Let's Plays, therefore the one most likely to have new LPers get views from the general public, and that is not going to change for some time I think. And it's the general public's support, not the niche enthusiasts (unless they are large enough a group), that LPers need.
But then for Youtube it's not about art. It's about lawsuits and revenue loss.