When viewing the photos or videos in your photo library, you can select between the following view modes:
Thumbnail view: Displays all the photos or videos from the group “All” or from a selected album as thumbnails.
Single item view: Displays one photo or video at a time as a larger image.
Full screen view.
To select the view, click the View thumbnails, View single item, or View in full screen icon buttons above the content area. You can also double-click a photo in the thumbnail view to open it in the single photo view, and vice-versa.
To start a video, double-click the video thumbnail and click the play button on the video.