diff --git a/active_projects/uncertainty.py b/active_projects/uncertainty.py
index 2c385c8c..1af18595 100644
--- a/active_projects/uncertainty.py
+++ b/active_projects/uncertainty.py
@@ -1727,7 +1727,7 @@ class IntroduceDopplerRadar(Scene):
         words = ["Original signal", "Echo"]
         for graph, word in zip([pulse_graph, echo_graph], words):
             arrow = Vector(DOWN)
-            arrow.next_to(graph.peak_point, UP, SMALL_BUFF)
+            arrow.next_to(graph.peak_point, UP, MED_SMALL_BUFF)
             arrow.match_color(graph)
             graph.arrow = arrow
             label = TextMobject(word)
@@ -2035,7 +2035,9 @@ class IntroduceDopplerRadar(Scene):
         sum_graph.background_image_file = "blue_yellow_gradient"
         return pulse_graph, echo_graph, sum_graph
 
-
+class MentionPRFNuance(TeacherStudentsScene):
+    def construct(self):
+        pass
 
 
 
diff --git a/extract_scene.py b/extract_scene.py
index 0d21e8a7..cec13bdf 100644
--- a/extract_scene.py
+++ b/extract_scene.py
@@ -95,6 +95,7 @@ def get_configuration():
       "save_pngs"       : args.save_pngs,
       #If -t is passed in (for transparent), this will be RGBA
       "saved_image_mode": "RGBA" if args.transparent else "RGB",
+      "movie_file_extension" : ".mov" if args.transparent else ".mp4",
       "quiet"           : args.quiet or args.write_all,
       "ignore_waits"    : args.preview,
       "write_all"       : args.write_all,
@@ -237,6 +238,7 @@ def main():
          "write_to_movie",
          "output_directory",
          "save_pngs",
+         "movie_file_extension",
          "start_at_animation_number",
          "end_at_animation_number",
       ]
diff --git a/mobject/vectorized_mobject.py b/mobject/vectorized_mobject.py
index a3ac3372..0e4cb237 100644
--- a/mobject/vectorized_mobject.py
+++ b/mobject/vectorized_mobject.py
@@ -54,10 +54,14 @@ class VMobject(Mobject):
         if fill_opacity is not None:
             self.fill_opacity = fill_opacity
         if family:
-            kwargs = locals()
-            kwargs.pop("self")
             for mob in self.submobjects:
-                mob.set_style_data(**kwargs)
+                mob.set_style_data(
+                    stroke_color = stroke_color,
+                    stroke_width  = stroke_width,
+                    fill_color = fill_color,
+                    fill_opacity  = fill_opacity,
+                    family = family
+                )
         return self
 
     def set_fill(self, color = None, opacity = None, family = True):
diff --git a/scene/scene.py b/scene/scene.py
index fda15aaf..09c6ffa1 100644
--- a/scene/scene.py
+++ b/scene/scene.py
@@ -380,7 +380,7 @@ class Scene(Container):
                 animations.pop()
                 #method should already have target then.
             else:
-                mobject.target = mobject.deepcopy()
+                mobject.generate_target()
             #
             if len(state["method_args"]) > 0 and isinstance(state["method_args"][-1], dict):
                 method_kwargs = state["method_args"].pop()
@@ -570,18 +570,23 @@ class Scene(Container):
             FFMPEG_BIN,
             '-y', # overwrite output file if it exists
             '-f', 'rawvideo',
-            '-vcodec','rawvideo',
             '-s', '%dx%d'%(width, height), # size of one frame
             '-pix_fmt', 'rgba',
             '-r', str(fps), # frames per second
             '-i', '-', # The imput comes from a pipe
             '-an', # Tells FFMPEG not to expect any audio
-            '-vcodec', 'mpeg',
-            '-c:v', 'libx264',
-            '-pix_fmt', 'yuv420p',
             '-loglevel', 'error',
-            temp_file_path,
         ]
+        if self.movie_file_extension == ".mov":
+            # This is if the background of the exported video
+            # should be transparent.
+            command += ['-vcodec', 'png'] 
+        else:
+            command += [
+                '-c:v', 'libx264',
+                '-pix_fmt', 'yuv420p',
+            ]
+        command += [temp_file_path]
         # self.writing_process = sp.Popen(command, stdin=sp.PIPE, shell=True)
         self.writing_process = sp.Popen(command, stdin=sp.PIPE)
 
diff --git a/topics/light.py b/topics/light.py
index 67f1458c..9ba8d75c 100644
--- a/topics/light.py
+++ b/topics/light.py
@@ -537,7 +537,7 @@ class Spotlight(VMobject):
                 new_submob = self.new_sector(submob.inner_radius,dr,lower_angle,upper_angle)
                 submob.points = new_submob.points
                 submob.set_fill(opacity = 10 * self.opacity_function(submob.outer_radius))
-                print "new opacity:", self.opacity_function(submob.outer_radius)
+                # print "new opacity:", self.opacity_function(submob.outer_radius)