import vsexternal
import sys

core = Core()
avs = core.avisynth
^^^ boiler-plate stuff ^^^
avs.LoadPlugin("ffms2.dll")
a = avs.FFVideoSource(source='D:/dl/Super Size Me/Super Size Me.avi')['video']
vvv boiler-plate stuff vvv
a.output(sys.stdout, 3, 1)