Flash player not working for my Mac high Sierra?

In order to provide assistance, you need to provide the information being requested.  If you're unsure what the request is, ask for clarity. Currently, you're not providing sufficient information for us reproduce the error.   A Google search for vipbox returns several sites (e.g. www.vipbox.st and https://www.vipbox.live/ ) that are unreachable and return 'the site can't be reached' error, and several sites (www.vipbox.tv and www.vipbox.me) that contain many channels, which is not helpful as we don't know which one you are having problems with.

I can say that, usually, the "error loading media...File could not be found' error is a content issue and not Flash Player issue.  I would recommend contacting the content provider for assistance and provide them with specific information, which includs the exact link to the content that is not working.

To give you any useful advice, I'm going to need to know more about your computer and browser:

https://forums.adobe.com/thread/1195540