I have some beef with your review of Deathly Hallows Part 1. As to the first criticism of the double agent scenario, I didn’t find his action bothersome. It seemed reasonable to keep up appearances. To stay quiet would’ve appeared suspicious given that both sides know he is a double agent, Voldemort expected information. Not to give Voldemort anything would’ve damaged his credibility. Perhaps this is made more clear in the books, but it didn’t strike me as odd in the movie.
The other criticism, on the defensive spells of the house, I thought was actually a bit surprising considering it is addressed in the very scene. Who put these defensive spells on the property? The Ministry. Just before the attack on the wedding reception, they hear a voice that tells them that the Ministry has been infiltrated, which means the protective spells are gone, allowing an attack on the property.
I’ve heard the latter explanation given — but only from people who already knew the explanation from the books. It may be that there’s enough information in the film to figure it out, but it wasn’t clear to me on first viewing, anyway.
On the prior point, is the agent’s cover — and the damage done if he doesn’t produce the information — really so crucial that the lives of Harry’s associates can readily be sacrificed for it?
For that matter, isn’t the double agent’s “declared” status at this point now with the villains? What bona fides does he still have, or is he known by Voldemort to have, with Harry’s inner circle of defenders, by virtue of which he would necessarily have the secret information in question — and so certainly that the failure to produce it would blow his cover?
What exactly does the double agent ultimately accomplish by preserving his cover? After sacrificing Mad-eye Moody and potentially others in the battle over Little Whinging, does he ultimately serve any greater purpose on the good side? Or does his double agentry ultimately serve only Voldemort? Did Moody die for nothing?