This being a publicly available index pointing to data stored, I can only assume that encrypted or not the owner of 'mega' is still liable for any copyrighted material hosted.
Are you serious? You expect them to scour the internet for third party websites and then scrape them for links? How are they even supposed to know whether a particular instance is infringing or licensed? What happens when the third party site prohibits scraping?
It isn't their job to be the copyright police. You cannot fix the problem of copyright enforcement being too expensive by foisting the cost onto a third party -- that doesn't fix that it's too expensive, it's just a textbook case of copyright owners engaging in the economic pollution known as externalizing costs.