This is what I think they did, because the particles look the same every color change. Built the particles the way they like them. Added a color matte behind them. Used the camera or put them both in the same group and increase its scale for the time speed up. Added a dissolve at the end of the “zoom in”. Duplicated that same graphic two more times and changed the color matte color. Placed the second group below the one prior where the dissolve started and it should look very similar. Hope this helps.
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