Unfortunately the screensaver clock is not working together with background mode and will be disabled if background mode is enabled. Only if this initialisation fails (on MacOSX versions older than El Capitan (10.11) or not supported Macs(usually Macs older as Mid 2012 except Mac Pro models from Mid 2010 with supported graphics card)) it tries to initialise OpenGL for rendering(as it was default between release 1.0 till 1.4.0). When started AnimatedGif tries to initialise Metal as first choice for rendering. Since release 1.5.0 AnimatedGif supports Metal(API) for rendering. Later OS versions of Big Sur starting with 10.5.2 make the Sandbox a bit more open and at least allow selection of local user files. Note: AnimatedGif is not working with Catalina(10.15-10.15.7) and early versions of Big Sur(before 11.5.2) since screensavers are to strong sandboxed in this versions of macOS(this means no GIF files can be selected or read from local disk and also background mode is broken), see issue #57 and #63. Since 1.5.1 also animated PNG (Animated Portable Network Graphics (APNG)) are supported (starting with OSX 10.10). In case of a selected directory the option panel of screensaver will let you choose a time between 1 and 30 minutes after which the GIF file is randomly changed. You can either open only one single GIF file or you can choose a directory that contains more than one GIF file. The background mode can be enabled under 'Screen Saver Options' in macOS. It also has a background mode to let you run the gif as a desktop background (or wallpaper).

AnimatedGif is an screensaver for Mac OSX / macOS that plays animated GIFs.

Convert gif to screensaver