Not sure of the point you're trying to make. Is it 1. the D-Day landing was fake because there are no aircraft in the sky, or 2. that balloons, dirigibles, and airships flew and were effective after 1937. If it is #1, then common sense and logic dictates the following response. The airspace above and around the landing beaches was unsafe to any aircraft - both friendly and enemy. The Barrage Balloons were cabled to altitude to foul and cut wings off of airplanes. The total concentration of anti-aircraft guns over the beaches and roadsteads, both on ship and batteries ashore was phenomenal. No allied pilot would risk a flight into that airspace, and would have been briefed to stay well out of the area. It was too easy for a lookout on a ship to mistake friendly for enemy and as soon as one gun starts firing they all would start. Research the USS Enterprise pilots who were flying to the Ford Island airfield soon after December 7th, 1941. An enemy pilot would risk it by that point only if the value of the target warranted the risk. By late 1944 the Japanese would and did risk those type of "suicide attacks". For defense of the beachhead any fighters would stage well off the beachhead area and were able to vector toward enemy aircraft based on effective radar intercept procedures. If it is #2, then be aware that the commercial transportation aspect of the airship died with the Hindenburg and various other national and international disasters. The big Airship theory was untenable, both in cost, materials, and volume of gas needed. Hydrogen was plentiful but very dangerous. The use of Blimps was cheaper, easier to construct, and safer gas-wise (helium), as they are today. The crew was much smaller, sometimes as small as two. Their speed approximated the average convoy speed, the linger time was only limited by fuel stores onboard, and they increased the visibility and coverage above and below the surface. You have a scene in the video where you see about six dirigibles in a hanger built to hold one prewar airship. Airships were too large and unwieldy due the vagaries of weather and the volume of helium necessary doomed them to the deadly lighter-than-air hydrogen. So in summation I see nothing out of the ordinary with what you hint at. I hope this explains things.