ND filters on a moving device (a drone in the air or a person moving around with a hand-held SLR) is not going to do much more than reduce your shutter speed. Unless you want things blurry on purpose for some reason, take it off.
For video, you also do not need ND filters. People that use them do it to achieve a cinematic effect. That is, it slows the shutter speed down to add more motion blur to video, which is what film cameras did (more or less). If you're hip to that and you want it, then use the ND filter that will give you a shutter speed that is roughly twice that of the frame rate. For example, if you select a frame rate of 24, then you want a shutter speed of somewhere around 1/50 (24x2=48).
Even if you are hip to what that does, that doesn't mean that you have to do it. You can shoot without ND filters and get a sharp, crisp video because each frame was taken with a faster shutter speed. Even if you're still shooting at 24fps, this is true. And if you shoot at an even higher FPS, such as 60, you're getting the HFR (High Frame Rate) look.
So you should do some reading to familiarize yourself with those modes of shooting, decide what you want (which can change from shoot to shoot, depending on what the subject is), then decide what filters to put on.
Chris
PS: ND filters are indeed used on hand-held SLR still cameras, but they're typically used while the camera is on a tripod to reduce vibrations. That's a use that not applicable to drone still photography.