vimeo and youtube videos at 100% and resize on browser window resize too on tumblr blogs. patch to: http://oscargodson.com/posts/making-vimeo-videos-bigger-than-500px-on-tumblr.html

bigger-tumblr-videos.js

// MAKE SURE TO CHANGE "container" to the name of the ID of the container that's
// 100% width you want the video to fit in
var resizeVideos = function () {
  console.log('resized')
  var iframes = document.body.getElementsByTagName('iframe')
  ,   newVimeoWidth = document.getElementById('container').offsetWidth
  ,   newVimeoHeight = 'auto';
  console.log(newVimeoWidth)
  for(x in iframes){
    if(iframes[x].src && iframes[x].src.indexOf('player.vimeo.com') > -1 ||
       iframes[x].src && iframes[x].src.indexOf('youtube.com') > -1){
      if(newVimeoHeight == 'auto'){
        newVimeoHeight = ( newVimeoWidth * 9 ) / 16;
      }
      iframes[x].width = newVimeoWidth;
      iframes[x].height = newVimeoHeight
    }
  }
};
  
window.onresize = resizeVideos;
resizeVideos();