Open the application "Shop" -> "Plugins" -> "Gallery+".
Turn on the plugin by checking "Enable".
After switching on, the plugin automatically displays a Gallery+ on the product page by using the hook "frontend_product" in the standard location.
Just remove the current image gallery from template.
This method is more preferable and faster.
Disable the "Use the frontend_product" option.
Use this example (from "Default 3.0" theme) for replace current gallery to Gallery+
How to add video?
Open the video on YouTube you want to put in the Gallery +.
Right-click in the video window and select "Copy video URL".
Open the Store application -> "Products" -> select the desired product -> "Edit" -> "Photo and video" -> "Video manager" -> click the "Add" button, paste the URL in the "Video URL" field, click "Save".