"The footage is from the movie 'Kato Hayabusa Sentotai' filmed in 1944 by Toho Co, screenplay by Kajiro Yamamoto."
So that's what Toho did before the Godzilla movies. Wouldn't it be great if Aces High had a Godzilla monster that you could drive around? It would be thirty stories tall, atomic breath, claws, perhaps it could lay eggs on the enemy bases and spawn Godzookis, which of course can fly.
Warbirds had one, a very long time ago:
http://www.virtualpilots.fi/feature/articles/warbirdseastereggs/Seriously, though, it would be fascinating to know what was going through the filmmakers' minds in 1944. Did they know they were losing the war? And that their film would be used to make young men feel better about being sent to certain death? I bet they had some sleepless nights when it was all over.