To display YouTube, Vimeo and Wistia, videos, you just need to paste the video URL, or share URL of the video in the data-src attribute. The same way you display images in the gallery. lightGallery will check the data-src attribute and if it is a video URL, it will create the respective video slide.
You can also provide poster image for each videos. Poster images will be loaded instead of videos. So user will be able to navigate to other slides by using mouse drag or swipe. Poster images improve performance, and maintain the flexibility of your gallery without effecting user experience. Videos will be loaded when a user clicks on the poster images. You can place poster image url in the data-poster attribute.