...there are a lot of sites/forums that are wired
to autoreject URL's posted in such areas as "reply" boxes
or forums. [discourage spamalicious advertising]
...entering a URL in a non standard [incorrect] format will evade automatic detection..but can still be
understood by the [human] reader.
..Youtube will reject/refuse to upload a viewer comment
if there is a URL in it. [drove me nuts before I figured
out what was going on.]