Upload the multiple images and youtube video on product review section. Once admin view the images and video in admin review section and enable the review.
In product details page review section user to view the image in light box and view the video.

For Demo
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http://democart.meximas.com/index.php?route=product/product&product_id=40

For Demo opencart 2
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http://democart.meximas.com/newoc/index.php?route=product/product&product_id=40