Flash became popular in the early 2000s for good reason - it added interactivity and polished design to the Web. Over the last few years, Flash has been operational and has been very important when using websites like YouTube and Hulu, among other sites.
However, with the emergence of HTML5, especially since the beginning of 2016, the Flash ad has seemingly become useless and has lost trend over the past few years. There are predictions that showing Google will finally close this ad type by the end of this year, 2016. I also predict that the majority of advertisers will need to shift their video ad supply to be delivered in HTML5 format, while currently, about 30% of the ads worldwide are in the HTML5 player (according to Selectmedia’a server stats from Aug/2016).