If the court rules that yes, the Dutch site also infringes copyright, it basically breaks how the internet works. You are liable for copyright infringement on any content linked to from your site. Imagine a forum, for instance..
First case seems to be fine as well. Unless of course you're hosting the images yourself, then you need to get permission.
As an example, I would think a link that allowed someone to get around the requirements to login to view something (maybe username/password as query parameters or something?) would be considered illegal.
Now, if a user on a private page, marked something as public, but did not publish the link, then it would be legal as you could argue that its freely available.*
* Not a lawyer, so just my own understanding.
so GreenStijl can't just host the pages anonymously on mega.com and link to them.. in that case they would deemed to be part of their website.
1) Linking to photos that you don't have authorisation to use on your website isn't copyright infringement.
2) Linking to a website that doesn't seek authorisation to use photos on their website.
To me it reads like the latter, in which case how is one meant to know if a website has sought and gotten authorisation for each photo they use?