Why you can't just screenshot an NFT

There are still several problems with NFT art. 

1) Anyone can create/mint a NFT of an artwork without the artists. Technically they can request the site to remove their art from the listings but what if they refuse, most artists can't afford to go through legal actions to prevent misuse of their work. 
2. Currently most of these really expensive NFTs have their price tags cuz of their artificial rarity. What incentive does the artist have to not change the sold artworks to something less rare(As you only hold the LINK to the artwork in the datebase, not the original art) or even  produce a even more rare artwork after the current rare artwork is sold?
3. Everything that can be done with NFT art can be done without the use of blockchain technology just like you mention in the video. An institution setup to verify and sell digital art works can be done without using something as inefficient and environmentally harmful as an blockchain tech.