Add motion blur to pre-rendered animation and video files in Final Cut Pro

If you have Motion, you can render out your animation with motion blur, you only need to turn it on.

You can specify the motion blur settings in the project properties.

If you publish the animation as a generator or title, the motion blur settings you set will be used with the template as long as you have turned the Motion Blur render setting on.

If your machine has the horsepower, you can increase the number of "Samples". You might want to do some research for what would be the best Shutter Angle settings... but 360º should be adequate for "general purposes".

The motion blur in Apple Motion will only work on the elements you created in Motion. If you want to add motion blur to an existing video clip, there's no built-in, ready to use tool. You'd have to retime it, add motion blur (if it even works properly there), export, and hope for the best. I believe AE has a tool for this.

The motion blur in Motion will handle everything. For video clips, all you need to do is import them, set the motion blur preferences and export them. It's a "global setting". Motion blurs are not specific to any object (along with frame blending and field rendering.)

Can I use Optical Flow in Final Cut Pro to generate motion blur in any way?

You can't tell what kind of file it is until you examine it. Can you share a short sample?

Upload the file to WeTransfer →Send to yourself →Post the link you obtained. Shared via email notification.

Motion blurs can be added to FCP clips as effects... I've done it.

If allowed: https://www.youtube.com/watch?v=0WNeaAy_1Ts

With 4 samples/360 shutter angle. This gif is only 15fps though — hard to tell...

Here's a smaller 23fps sample: