Installation:
open openIV and enable edit mode. Go to C:\Games\Grand Theft Auto V\mods\x64l.rpf\levels\gta5\_citye\sunset
and put the file in.

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UPDATE
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if you got the rca mod go to C:\Games\Grand.Theft.Auto.V\mods\update\x64\dlcpacks\rca\dlc.rpf\x64\sunset.rpf\
open ss1_lod_01_02_08_09_10_11_children.ytd
and replace the ss1_08_superlod file

if you don´t got the rca mod go to C:\Games\Grand.Theft.Auto.V\mods\x64l.rpf\levels\gta5\_citye\sunset\sunset.rpf\
open ss1_lod_01_02_08_09_10_11_children.ytd
and replace the ss1_08_superlod file

If you want to install the phonebox from the video also go to: \mods\x64h.rpf\levels\gta5\props\roadside\v_utility.rpf\
and replace both phonebox files.

before that I recommend like always to backup your file/s.
have fun,
mikesta ; o )