Back in the day Flash was a necessary evil, horrendous to program professionally but was capable of dealing with client side functionality such as videos and animation that the browsers at the time simply could not.

Meanwhile in the year 2015 browsers have moved on. JavaScript and css can handle all of these problems and html5 have gave us access to media built in.

Although Firefox is saying that it is blocking it because of software security reasons. In general people should be moving on to new technology. Even Adobe, Flash's owner, now focuses more on their production JavaScript frameworks such as Experience Manager (formally Adobe CQ) and EaselJS more specifically.

It'll be nice to see a rush of websites hopefully updating to html5.