Assuming paddoboy is not Fraser Cain, there are three parties (the author, the poster, the website) and two agreements (the author's license to the poster, and the terms of service of the website) involved in the described scenario. Now unfortunately, copyright is created the moment the article is fixed in a medium and lasts about forever absent an irrevocable grant of the article into the public domain. So what do we know about the license granted to the author? What are the exact terms under which copying is allowed and what is the nature of the copying allowed?
https://en.wikipedia.org/wiki/Public_domain
What is the duration of the license? Can the author change his mind? Can the terms change? Can any portion of the article be used for any purpose whatsoever? Turned into a movie? Incorporated into a volume of similar works? Does the right to copy transfer to any copies made by the poster?
A basic tenet of contract law is that you can't trade something for nothing. So when I am told that the general terms of the Universe Today site are:
If you want permission to reprint Universe Today stories
You have our permission. There, that was easy. You don’t even have to ask us. We’d appreciate it if you gave Universe Today credit, though. Just put a link in the story that says that it was
originally published on Universe Today. If would be even better if you credited the specific writer who worked on the story.
does that tell me there are no strings at all? No.
http://www.universetoday.com/248/contact-me/
One, this is not a contract unless at least some term imposes a binding obligation upon the poster. Are we to assume that two sentences after the smiley are non-obligatory? If not, then a link back is mandatory in the form given. If so, then for this to be a contract there must be an obligation elsewhere.
https://en.wikipedia.org/wiki/Consideration
Two, this is permission to "reprint" which could be read as a term of art. Generally, reprints are verbatim copies of books or articles. There's a whole host of derivative forms which are not reprints. Does this grant permission to translate this article into German? Into a stage presentation? If "reprint" is a limit on the form of copying allowed, then does it still count as a reprint if parts are missing or if you reedit it?
https://en.wikipedia.org/wiki/Reprint
Three, this grant has no fixed term. Even if we agree that a given use is a reprint and any obligations have been met, that permission is ephemeral and could be revoked by the author (or heirs/successors) at any time. But copyright law was created in a time of books and newspapers. So end-of-term just required no additional volitional copying. In the computer age, every website visit is a new copy. So a grant which does or could run out is a source of problems.
Four, the poster does not control the website. Indeed, after a few hours the poster cannot even edit his own contributions. So even if the poster was aware of limitations on the form of copying, he is not the actual entity doing the reprinting.
Introducing party number three: the website. The website has terms of service which are linked at the bottom right of every page.
We reserve the rights to remove or modify any Content submitted for any reason without explanation. Requests for Content to be removed or modified will be undertaken only at our discretion. We reserve the right to take action against any account with the Service at any time.
You are granting us with a non-exclusive, permanent, irrevocable, unlimited license to use, publish, or re-publish your Content in connection with the Service. You retain copyright over the Content.
http://www.sciforums.com/help/terms
Non-exclusive means the website won't sue the poster if the poster reposts his content somewhere else. Permanent means what the poster gives the website, is given for all time. Irrevocable means the poster (and heirs and successors) doesn't have the option of changing his mind in the future. And unlimited means unlimited. (SciForums: The Motion Picture has been in development for years, but Hugh Jackman has agreed to play James R if the thing is done as a Hollywood-style musical. Talks continue.)
The thing is, for the privilege of posting here, the website demands more right to the Content than the poster has secured from the author. Moreover, the "permission to reprint" does not authorize the poster to pass on the mechanical task of reprinting on someone not in his employ. In addition to the public domain option cited above, an irrevocable license like the Creative Commons (of type CC0) grants most of what is required by the website. These are very broad rights demanded, which is why these terms of service encourage the poster not to copy articles but to post
original content.
https://en.wikipedia.org/wiki/Creative_Commons_license
How then does any copying gets approved? It's a balancing act.
https://en.wikipedia.org/wiki/Fair_use
On top of the terms of service, we have a secondary document outlining what guidelines the website endorses as a rule of thumb. This document cannot trump the absolute tyranny of terms of service, but helps set standards for when posters and agents of the website come into conflict.
F. Copyright
F1. Material published online is protected by the same laws that apply to books, videos and music.
F2. The copyright in a member’s posts remains with the original author. By posting to sciforums, you give us permission to publish your posts anywhere on the site.
F3. It is illegal to copy or republish material from sciforums (or elsewhere on the internet) without the express permission of the copyright owner.
F4. Under the laws of many countries, limited quotation of material is permissible in the context of comment, review and/or criticism. This does not in general permit the reproduction in full of complete works (e.g. song lyrics or news articles).
F5. Where you reproduce part of a work in a post, you must include a link to the original source, along with appropriate acknowledgement – at a minimum the author’s name and the name of the original publishing source, but consider also supplying the original date of publication and other relevant information (e.g. ‘US shares fall further’ by A.Writer, New York Times, 11 September 2015.)
http://www.sciforums.com/threads/sciforums-site-rules.142880/
DaveC426913 makes a point that we could use a F6, possibly along the lines of "Where you reproduce part of a work in a post, you must delineate that part from the rest of your post and comment, review or criticize the work."
and need to resort to such nonsense [which I find rather weird] as labeling me as a science cheer leader! 
