You don't need a legal document to get videos taken down from youtube. They will do it simply by request from the aggrieved party. All they have to do is cite copyright infringement and youtube will take it down.

Yes - If it's a commercial product the owner of the product can have it taken down fairly easily. There's a form to fill out and it's usually gone within 24 hours. If the channel has too many reports of that nature, it is often completely disabled and the account holder will not be able to monetize future accounts.

A not-insignificant amount of my day-job is filing copyright infringement reports. YouTube is really good about yanking videos, Google (Blogspot, mostly) is OK but their form is much more time consuming to fill out.

It does have to be an upload of published material though. Someone just revealing a trick is not violating anything unless they claim to be associated with the creator/owner of the material being revealed.

I think this highly depends on applicable local or international law. For blatant copies (e.g. if somewhat would upload a Penguin live lecture) there is a clear breach of copyright.

For exposure ("XYZ revealed" videos) that may be different. At least in my home country (Germany) it would be diffcult. Not being a lawyer I know that "ideas cannot be copyrighted." So exposing an idea would be legally OK, albeit not ethical.

Between the two, there may be gray areas.

Ideas could be patented, but then again patents must be published. So if you invent a new version of a coin box and patent it, somebody could actually read it in the patent documents and reveal it. If they started selling the boxes as such, that would be another story.

Anyhow, I'm no lawyer, I might be wrong.

Have you tried contacting Youtube? I don't think it's a good idea to engage as this might infuriate the poster,
only causing him to leak more.

"Magic and Illusion" youtube user has infact been removed for "reported violations"! I'm happy.