I guess its fine if you edit it and use it yourself and only post general videos regarding your escapades - and not share the actual track/environment widespread on the forum, however I do suppose that any piece of game or property is shielded by some kind of content rights/property rights that prohibit extensive altering of the game to some extent..
http://mttlr.org/2012/11/gaming-mods-and-copyright/
"This means that mods are “legal” only insofar as game developers suffer them to be so; the moment a developer finds a mod distasteful, it can be found to infringe copyright."
Sometimes the game itself may not necessarily state anything in the T&Cs regarding modding or game alterations but instead the game and developers themselves are covered already by mainstream rules.
In short, if the developers/moderators think what you are posting/doing is somewhat not allowed, then its illegal abd automatically deemed so - even if it wasn't originally stated
http://mttlr.org/2012/11/gaming-mods-and-copyright/
"This means that mods are “legal” only insofar as game developers suffer them to be so; the moment a developer finds a mod distasteful, it can be found to infringe copyright."
Sometimes the game itself may not necessarily state anything in the T&Cs regarding modding or game alterations but instead the game and developers themselves are covered already by mainstream rules.
In short, if the developers/moderators think what you are posting/doing is somewhat not allowed, then its illegal abd automatically deemed so - even if it wasn't originally stated