Four years ago, we wrote about YouTube’s early support for the
<video> tag and how it performed compared to Flash. At the
time, there were limitations that held it back from becoming our
preferred platform for video delivery. Most critically, HTML5
lacked support for Adaptive Bitrate (ABR) that lets us show you
more videos with less buffering.
Over the last four years, we’ve worked with browser vendors and
the broader community to close those gaps, and now, YouTube
<video> by default in Chrome, IE 11, Safari 8 and
in beta versions of Firefox.