Is possible to stream encrypted content (DRM) using only Javascript and HTML5 audio and video tags, leaving behind and not using the SWF approach?
Yes - you can playback encrypted content with certain browsers just using HTML5.
Let's look at the entire workflow.
On the server side: you have to encrypt your content and provide a license server.
for example:
On the client side: you need a browser that supports encrypted media extensions (EME).
Netflix started working on it two years ago: http://techblog.netflix.com/2013/04/html5-video-at-netflix.html and supports it now on a variety of browsers and platforms.