Earlier quoted context omitted.
I think I'm missing something. Why not just install the Flash player from Adobe?
I'm not the person you asked, but here's my reasons. I'm on Linux and there no longer is a supported version of Flash by Adobe. (Apparently there is some NPAPI to Pepper bridge though, to get Chrome's Flash working in other browsers.) I already uninstalled before that, because I wanted to force HTML5 for sites that dynamically switch between Flash and HTML5 and because I wanted to nudge more sites to support HTML5 by…
I'm using Firefox on Ubuntu with Flash (flashplugin-installer) and it's still receiving updates. It's an older version, but it has been working fine with every Flash site I've visited so far.