Hi,
If you add your videos in the product description with the "loadposition" system of Joomla, you can restrict the display of the modules based on the access of the customer. Then, in your product, you can use the "user group after purchase" setting to add a specific group to the customer after the purchase. And finally, you can configure that user group for the access selected in the module so that the module will only be displayed to users being added to the group added by the purchase of the product.