Media Hovers plugin can create a gallery of image thumbnails which will play video on hover. Gallery can be placed anywhere in your page. Media Hovers also supports lightbox mode where images and videos can be viewed in a larger mode. Lightbox can also contain Youtube videos, Vimeo videos, or any custom iframe. Gallery supports several different grid modes (tiles, masonry, justify, carousel) and many different image skins. Images can be grouped in categoreis (tags) and filtered in the page.

This plugin creates gallery of its own, it does not interact with other galleries neither it can change other galleries in 3rd party plugins or themes.