I don’t see an attachment but gave it a quick try myself and got it to work. To achieve the same effect as in the video you have to consider the value ranges and clamping.
- Create a plain effector
- In the field list create a Linear Field (bottom) and a Random Field (Top)
- Set the blending mode of the Random Field to “multiply”
- Select the Linear Field, go to the Remapping tab and disable “Clamp Max”
You can think of all Field output as multipliers for whatever effect you specified in the Parameter tab. What we want is to start with no effect and end with full effect but with offsets for each clone. The Linear Field produces by default produces values between 0 and 1. If we now multiply with a random value (again between 0 - 1) for each index, we have a problem. Let’s say our random value for clone 7 is 0.5. If the Linear Field spits out a maximum value of 1, then this will never reach 1. By disabling the clamping in the Linear Field the value output will keep increasing after the range that is visualized in the Viewport. Once we have reached a value of 2 from Linear Field and multiply that with the 0.5 of the Random Field we reach the final state of the effect because the Field List itself is clamped to an overall 0-1 range, too. You can disable that (button at the bottom right) to see the difference.
Hope that makes sense.