To put it simply (in addition to what others have said on the issue), your reasoning given when using the "Other" option was as follows:
This answer looks more like a comment to me because it does not offer much besides a link to the external resource.
This can easily be summed up by the already-existing "Not An Answer" option:
This was posted as an answer, but it does not attempt to answer the question. It should possibly be an edit, a comment, another question, or deleted altogether.
That said, there seems to be a fair amount of debate on the topic (or on similar/related topics):
- http://meta.stackoverflow.com/questions/135920/why-are-accepted-answers-immune-from-flagging-link-only-answers-as-not-an-answer
- http://meta.stackoverflow.com/questions/72000/should-there-be-a-policy-about-one-link-only-answers
- http://meta.stackoverflow.com/questions/140062/flag-declined-link-only-answer-subsequently-deleted
And there's even more to be found when searching MSO for "link-only answer"...