You have edited the wrong file, namely the newsfeed.js file. You should be editing the config.js file which resides is the MagicMirror/config folder. If so, you should revert all your changes to their original state and edit the config.js entry for the newsfeed module. It should look something like this. I tested your url for NOS Algemeen and it works fine with the module.
{
module: "newsfeed",
position: "bottom_bar", // This can be any of the regions. Best results in center regions.
config: {
feeds: [
{
title: "NOS Algemeen",
url: "http://feeds.nos.nl/nosnieuwsalgemeen",
},
{
title: "BBC",
url: "http://feeds.bbci.co.uk/news/video_and_audio/news_front_page/rss.xml?edition=uk",
},
]
}
},
Screenshot
<img src=https://www.dropbox.com/s/4umt2lz4m75eg6j/newsfeed.png?raw=1 />
