You don't state where in the manual this is stated but since these cameras use a mechanical cooling device its most likely to do with the cooling control refesh rate. Too slow and you may miss small fast changes in temperatures or be inaccurate. If unsure ask FLIR they will clarify for you.
This refers to the rate at which Infrared camera scans/refreshes on capturing the image.
For 1st moving items, we prefer 60Hz, slow moving items we go as low as 9Hz. But we also do have the 25 & 30Hz cameras.
John O'Brien was right, I was only clarify what he said
Hope this helps. Further clarification please contact me on my email: email@example.com. Flir Kenya