In particular, I've heard that is makes content hosts (literally everyone: youtube, twitch, twitter, reddit, even here through embeds) criminally and civilly liable for copyright infringement if they host copyrighted material, even if unintentionally. It's no longer enough to just remove the content as quickly as possible; if it's on there for even a second they can get fined.
There are two possibilities if this passes: either those hosts will disallow any and all gaming content (in a moment completely destroying the let's-play, E-sports, and online review industries), and severely restrict uploaders who aren't "approved" (read: privileged though paying lots of money).
Or: they'll tell the EU to go fuck itself with a barbed-wire dildo, (which they can do if they're based in the USA) and simply block all content in member countries. Effectively, you just won't be able to access youtube, twitch, etc. in those countries anymore, similar to China except not as widespread.
Of course, just like with China, people will find a way around it. The end result will be zero if you're not in the EU, and an inconvenience if you are.