Basically what it says in the title... 
I can scrape a group feed if it's open, but if it's closed then it doesn't work. Obviously that would make sense if I didn't have access, but if the account I'm logged in with is a member should it not work?
I'm not sure, but from what I understand, it requires admin role of the group/page.
Thought I'd managed to do it before, but must have dreamt. Figured an external workaround. Thanks!