Advanced Gallery

Add the advanced-gallery class to a module group:

Then add Image modules inside creating the layout you want and choosing your thumbnails:

If you want to include a caption use the Image alt text. You can use simple HTML tags as well. e.g. Sweet & Tasty<small>with Fresh Berries</small>

If you use a smaller image for your thumbnail you can specify a link to its full version:

Or if you want to add a YouTube video, you can specify its URL instead:

Then, add the video class to that module:

You can find this already implemented within the Act21 Advanced Gallery template.