General help

This is a perennial question and I do not think there has ever been a clear, concise or workable answer to it yet. There is always copyright or other intellectual property rights, but the bottom line is the same. Unless you are prepared to chase the bunny with a lot of money, I think you may be on a loser. 

You can try to work an error trap into the script that controls the viewing of the video. Something like: 

     <video oncontextmenu="return false;" id="my_video" width="800" height="600" controls autoplay>

          <source src="https://path.to/my/video.mp4" type="video/mp4">

    </video>

And I have no idea if that will work or not but it seems logical and makes sense (to me anyway but I am a long way from my code writing days and getting further away every day). 

You can try to hide behind an emulator, however that works.

You can try to do any one of hundreds of things, but I do not believe any of them actually work. 

Best of all, don't put your videos up so anyone can download them. That will stop them. 

You can't.

Anything that comes over the internet can be downloaded. Don't let anybody tell you any different. 

There are readily available browser plugins that make it trivial.