It is the art, that is how they get you. They own the art (Models/Textures) of the game, by posting a video you are making a derivitive work, which is how they can hold it on copyright grounds. It has nothing to do with the name etc ... anyone could potentially go trademark World of Starcraft today and if it wasn't already trademarked, then even with all of Blizzard/Activison's money and power, I doubt they would be successful at getting it revoked, simply because if you have that much money and you wanted the name, you should have trademarked it earlier.
You are living my dream mate. Everything I do in the SC2 editor is simply to get noticed by a gaming company, such as Riot, Valve or Blizzard itself and make it as a game designer, this is simply because of one moment in time - back in late 2004 I gave Icefrog a Dota-like map engine, regardless how much my map sucked - it was the ideas behind the engine that were important - he used those ideas to further Dota along and now he is cashing in on it.
There are many people like me that contributed to Dota over the years, and are missing out. Why should Icefrog get all the cash? All he was ever truly good at was seeing the potential in other people's work, and piecing it together like a jigsaw puzzle. Dota is merely a collection of derivitive works, nothing more ... Icefrog has never once been a good designer nor has he ever been transparent about anything ... this is a bad thing.
This is the world of mod making ...
Go for it mate, never forget who you are.