It's really no big deal as far as I'm concerned. But the management of any forum is wise to not encourage their membership to drift. There are a lot of our members who belong to other forums as well. I haven't got enough time for here.
Copy/pasting any articles, pictures and material is fine. You don't even have to attribute it. Links to Ebay, Youtube, Aquabid, one's own website or blog, etc. are all fine.
You have the "response" technique right. I was notified on my User Control Panel.
Hi Vergil. Nice article you posted on that Water Quality thread. It's against forum policy to post threads from other forums. I would never say anything about it. I like as much info as I can get. But if a Mod comes along and deletes it, now you know why.
BTW, if you respond to a Visitor Message like this one. Type your response on the response page (click on View Conversation to get there). That way the person you're responding to gets a notification that you responded.