They are if they are derived independently from the text via discussion here or guesswork. ie. You can guess stuff. They aren't if, um, you raid Eliezer's dwellings and find yet to be published manuscripts, for example. Or torture Eliezer to find out his plans. Any source of knowledge that hasn't passed through the bottleneck of the text at some point.
Dclayh didn't reveal anything remotely privileged. Or anything that hasn't been speculated on ad infinitum.
dclayh was complying with the spirit of this request from Eliezer:
I came to realize in time that what I thought was a bug was a feature, however frustrating that may be for me, so please rot13 that comment with the warning "spoilers even if you've read all chapters".
[Update: and now there's a fifth discussion thread, which you should probably use in preference to this one. Later update: and a sixth -- in the discussion section, which is where these threads are living for now on. Also: tag for HP threads in the main section, and tag for HP threads in the discussion section.]
The third discussion thread is above 500 comments now, just like the others, so it's time for a new one. Predecessors: one, two, three. For anyone who's been on Mars and doesn't know what this is about: it's Eliezer's remarkable Harry Potter fanfic.
Spoiler warning and helpful suggestion (copied from those in the earlier threads):
Spoiler Warning: this thread contains unrot13'd spoilers for Harry Potter and the Methods of Rationality up to the current chapter and for the original Harry Potter series. Please continue to use rot13 for spoilers to other works of fiction, or if you have insider knowledge of future chapters of Harry Potter and the Methods of Rationality.
A suggestion: mention at the top of your comment which chapter you're commenting on, or what chapter you're up to, so that people can understand the context of your comment even after more chapters have been posted. This can also help people avoid reading spoilers for a new chapter before they realize that there is a new chapter.