I found this scriptfic to be completely random and silly, as advertised.
The opening speech is a but of a turnoff. I already know what Cate-as-Galadriel said in the movie, so instead of rehashing it in such a manner, why not give me more of your take? As is it makes it look like you think LOTR was stupid. Even if that's true, you should go for more of a "This is worthy of mockery" thing.
You seem to have the same problem in the body of your story -- you cleave too closely to the scene-by-scenes of the original, and you don't have to. This might be funnier if you gave yourself more room to roam afield.