HTML5 video
Support for HTML5 video has been steadily increasing. In June 2013, Netflix added support for HTML5 video. In January 2015, YouTube switched to using HTML5 video instead of Flash by default. In December 2015, Facebook switched from Flash to HTML5 for all video content.
Comparison of HTML5 and Flash
Tools for HTML5 are just starting to come to market; in the meantime, Adobe has released a first version of a Flash-to-HTML5 conversion tool for existing content and are working on creating new tooling for HTML5 as well, like Adobe Edge.