How do I set output video file name using python script?

Question

I'm using a python script to render my scene using the OpenGL render to get more speed, as the quality I'm getting is enough for my purposes.

I'm using this script:

import bpy
import sys                      # read argument from sys.argv
from bpy.app.handlers import persistent

@persistent
def do_render_opengl(dummy):
    bpy.ops.render.opengl(animation=True, view_context=True)
    bpy.ops.wm.quit_blender()

bpy.app.handlers.load_post.append(do_render_opengl)

I'd like to choose the resulting filename ( video123.avi for example ) from inside the python scrit.

I tried with bpy.context.scene.render.filepath = '//filename.avi' for example, but it looks it would work only for rendering as separate frames.

Thank you. Best Regards.