Finding a way to stop a moving object from blurring in my animation

I'd like for you to post a still shot from your video showing where the helicopter is blurred and out of focus.

Hi Garth,

If you pause the video at any frame you will see that there is no blur and each image is very crisp.

What you most likely see is flicker or strobing effect. (This is what I see playing it with VLC.)

This can be at least partly related to out of sync playback with the refresh rate of your display. Depending on your location (50Hz or 60Hz mains frequency), for example a frame rate of 25fps might produce better results. 

The refresh rate note above might only be worth a quick test, just to see if you will get some marginal improvement.

You can also improve smoothness by upping the frame rate to 50 or 60 fps.

Ironically, to make the movement appear smoother you actually need to blur the object in the direction of movement. It's called motion blur. This is how video and the human eyes work, not specific to Animate.

Generally speaking long shots with objects tweening across the screen are always problematic. It is better to stage and edit them in a way where in-shot movement is not so large or it is much faster or slower. 

In this case you've hit the worst combination.

If I was to try and save this shot, first thing to do would be to add a little directional blur and then speed up significantly as the helicopter gets closer to the camera. This is how the dynamic of an even movement should be conveyed in perspective anyway. Amplitudes between states should be much greater as the size increases while getting closer to the camera.

Hope this is somehow helpful!