youtube should not be a problem. even if you embed the video into your posting, the ad will be credited to the original owner (as far as i know). Some videos will not be available for embedding, but a link should be fine.
With forums etc things usually do not get hard. Ya, people into the hobby are nice, everybody copies from somewhere etc, but, and always there is a but. Let's look for example at TPT.
http://www.verticalscope.com/aboutus/tos.php?site=plantedtank.net
In particular " Without limiting the generality of the foregoing you may not make any commercial use of such content, either alone or in or with any product which you distribute, or copy or host such content on your or any other person.s web site or FTP server."
or
"All material on this site, including, but not limited to images, illustrations and multimedia materials, is protected by copyrights which are owned and controlled by PLANTEDTANK.NET or by other parties that have licensed their material to PLANTEDTANK.NET. Material from this Web Site or from any other web site owned, operated, licensed or controlled by VerticalScope Inc. may not be copied, reproduced, republished, uploaded, posted, transmitted, or distributed in any way. Modification of the materials or use of the materials for any other purpose is a violation of the copyrights and other proprietary rights held by the respective providers thereof. The use of any such material on any other web site, ftp server or network environment is prohibited."
So, everything posted here belongs to TPT and at any moment, if they wish, then may give you call. Is that gonna happen? Probably not, but I am just saying, that the truth is not on your side.
However, whatever you produce, it will be yours, and same rules will apply.
I just want to make sure, that I pointed out to, by no means is a sign of discouragement or something. In fact, i am personally looking forward to such articles/posts. Starting a blog probably is the best option, and you can go from there.
good luck.