This article explains how files uploaded with WordPress File Upload plugin can be added into NextGEN Gallery galleries.
NextGEN Gallery is the most popular gallery plugin for WordPress websites since 2007. It has more than 900k active installations and more than 1.5 million downloads every year. There have been several user requests, asking to integrate both plugins.
As of version 4.11.1, WordPress File Upload plugin includes options to add the uploaded files into NGG galleries. These options are in Interoperability section of the shortcode composer of the plugin:

To use this feature open the shortcode composer of an upload instance and go to Interoperability tab. Then turn on Add Uploaded Files to NextGEN Gallery option. When this option is activated, the other NextGEN options at the right will be enabled.
The following options are available:
NGG Gallery ID
(int) It determines the ID of the NextGEN gallery where files will be added. By default it is set to 1.
NGG File Description
(string)(optional) It defines a custom description for the files added to NextGEN gallery. This option accepts dynamic variables, such as user ID, username or values entered by the user in the additional fields of the upload form.
NGG File Alt Text
(string)(optional) It defines a custom alt/title text for the files added to NextGEN gallery. This option accepts dynamic variables, such as user ID, username or values entered by the user in the additional fields of the upload form.
NGG File Tags
(string)(optional) It defines a comma-separated list of custom tags for the files added to NextGEN gallery. This option accepts dynamic variables, such as the values entered by the user in the additional fields of the upload form.
NGG Exclude File
(on/off) It defines whether the files added to NextGEN gallery will have their Exclude property activated. When this property is active the files are not shown.
The files added to the NextGEN gallery can be managed through Dashboard / Gallery / Manage Galleries page just like all other gallery files.
For more information or questions you can contact us.
The Iptanus Team