message: Use createObjectURL instead of readAsDataURL for videos
diff: @@ -148,29 +148,21 @@ function infoForImageFile(matrixClient, roomId, imageFile) {
  * @return {Promise} A promise that resolves with the video image element.
  */
  function loadVideoElement(videoFile) {
  - const deferred = Promise.defer();
  -
  // Load the file into an html element
  const video = document.createElement("video");
  - const reader = new FileReader();
  - reader.onload = function(e) {
  - video.src = e.target.result;
  -
  // Once ready, returns its size
  // Wait until we have enough data to thumbnail the first frame.
  video.onloadeddata = function() {
  + URL.revokeObjectURL(video.src);
  deferred.resolve(video);
  };
  video.onerror = function(e) {
  deferred.reject(e);
  };
  - };
  - reader.onerror = function(e) {
  - deferred.reject(e);
  - };
  - reader.readAsDataURL(videoFile);
  + // We don't use readAsDataURL because massive files and b64 don't mix.
  + video.src = URL.createObjectURL(videoFile);
  return deferred.promise;
  }
  