As is displayed here: http://codepen.io/chriscoyier/pen/zbakI you can apply a filter to videos using css filters.
You define the filter and then you refer to it later when applying it to the video element.
var blur_name='the_blur';
master_video.style.webkitFilter='url(#'+blur_name+')';
master_video.style.mozFilter='url(#'+blur_name+')';
master_video.style.filter='url(#'+blur_name+')';
var blur_name='';
master_video.style.webkitFilter='';
master_video.style.mozFilter='';
master_video.style.filter='';
But how can i get the filter to not blur the controls of the video?
To accomplish this, you will have to use custom video controls. There are lots of resources out there that explain how to implement them, for example this article.
I've edited a fiddle I found on Google to illustrate this:
http://fiddle.jshell.net/td8Lao79/
I am applying a simple
filter: blur(4px);
to the video element, but you can define your filters in HTML and refer to them by ID if you prefer.