The browser vendors are queuing to say farewell to Flash, recently Google has decided to block Flash in Chrome and make HTML5 as default, before that, Mozilla has announced they’ll reduce Flash usage in Firefox browser. The patch which supposed to block non-essential flash content (by default) in Firefox 47 has been landed in Firefox 51 and activated.
Firefox 51: Block Some Non-Essential Flash Content by default
This patch, which aims to bring ‘enhanced security, improved battery life, faster page load and better browser responsiveness’ to the browser has been applied and will block ‘certain Flash content that is not essential to the user experience’. What this means is the first phase of flash blacklist has been enabled as an ongoing effort to reduce NPAPI plugin usage.