A video is not needed you simply fill out a Script Dialog then Click the create the output button at the bottom of the dialog.  You point the Script to the folder containing the Mockup templates to Populate,  Point the Script the Folder that contains the Collections of replacements images for each smart object layer in the Templates. Point the script to the folder you want to output populated  mockup save into. And you set  the script option for how you want the script to operate.  The process is completely automated. All you need do is set thing up properly for the automated process. Here I did not have the correct size images for your mockup so I used the script Edit option to have the script edit the replacement images into the existing objects instead of using the default operation the uses Replace Content.