I was mistaken. To achieve the necessary effect it is enough to add FX in a composition and randomize one parameter "Step 1" (parameter "Run" it is not necessary to start). And also to choose a clip in parametres "Layer N" and "Clip N".

Using the IRClipSA fx You can do it. You need set the random mode for parameters of "Run" and all "Steps N".

http://irworkshop.com/products/ir-clipsa-free

You can see FFGL fx's IR CosmicPack on my site. In this pack almost all fx are frame buffer for the delay effect.
site: http://irworkshop.com

for the "IR Array of Boxes" have preset "Time jitter", perhaps this is what you want.