Embedding youtube and vimeo video clips, photos too for that matter into posts, is easy. More about how at:
http://fksa.org/forumdisplay.php?f=17
Still looking into the whole soft, physically delete thing. It isn't as straight forward in the forum software as I would like. Everyone should know that posts deleted by users are hidden from users but not moderators. As far as I can tell there is no direct way to alter this but I am still checking. It may come down to simply aware of this and using some restraint.
BigR just reminded me of something. If you want to delete the content of a post, simply do that and put "edit" in its place and save it. No one will be able to read the original post. It is easy and avoids this entire issue.