I cannot agree with what the speaker says for a few reasons.
First, each and every one of the examples he used during his presentation are all covered under the fair use doctrine. Fair use allows the use of those media for (primarily) educational and satirical uses. So long as that is the case, he isn't supporting his argument at all.
Secondly, very few people can actually practice "common sense". As the saying goes, common sense isn't so common. Thus you cannot trust people to do the right thing with something you create. If, as an artist, you pour your heart into whatever art you create (sculpting, painting, manga, photography or whatever) and someone takes it and decides to put it into their own portfolio and say that they made it, how can that be right? Yet without the copyright protections that's what people do. They still do it, simply because it's so hard to enforce because most artists are so unknown that anyone looking at the portfolio will not likely have seen it before.
I am an amateur artist myself. I take great pains to keep my artwork my own, even though I want to share it with others. I don't want someone else taking credit for something I sweated and bleed for. I don't want someone to get a job that should've gone to me because they stole my work and claimed it as their own.
If you want to say "I'm not saying they should take your work, but they should be able to use it", then how is it fair that someone could take an image I create, put another image on top of it, or incorporate it into their own, and still take all the credit for it? What if my work is what makes their artwork the most appealing? Why should I not take credit for it?
Yes, you can call me selfish. I'm fine with that. But I put in a lot of work for every thing I create. I feel I deserve it. Anytime I use something from someone else in my art, I absolutely make sure to credit them when I post it.