FFT interpretation of time vector (simple)

Video data is three-dimensional: horizontal, vertical, and time.
None of the examples deal with images – let alone video data.

It is certainly possible to do a 3-d FFT, but I doubt that is your intent.
Tell us more about this video and exactly what you want to extract from it. Is it a pendulum swinging back and forth and you want the frequency?

This sounds like a situation where an FFT could be used – but it probably isn’t the best method.
If you do use an FFT, you would probably want to take a slice of the image across those frames so that you ware dealing with width and time. The slice would be selected as containing the periodic motion. Then an FFT would highlight periodic motion (with frequency spikes) along the frequency (time) axis.

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