第二行改成這樣
video=dgdecode_mpeg2source("1.d2v")

你若是用 dvd2avi 則改成這樣
video=MPEG2Dec3_mpeg2source("1.d2v")

Avisynth 2.55 以後最好都這樣寫
插件dll的檔名_function(.....)

avisynth 說明檔是這樣寫的

Starting from v2.55 there is DLLName_function() support. The problem is that two plugins can have different functions which are named the same. To call the needed one, DLLName_function() support is added. It auto-generates the additional names both for auto-loaded plugins and for plugins loaded with LoadPlugin.

但實務上好像不加入 插件dll的檔名_ 經常會出包
特別是 什麼什麼Source 之類的function