Dan is referring to one of the properties in the Scatter effect itself.
From the Scatter effect section of After Effects Help:
“Scatter Randomness
Specifies whether scattering changes at each frame. To animate scattering without keyframes or expressions, select the Randomize Every Frame option.”
A convenient way to look for answers yourself is After Effects Community Help search.
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Todd Kopriva, Adobe Systems Incorporated
putting the ‘T’ back in ‘RTFM’ : After Effects Help on the Web
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