My use of multimedia in Assemblies supports the narrative action rather than replaces it. I have tried using Google Docs here to store the slideshow for a Junior School (whole school) Assembly of 7-11 year olds.
At present, the Google Presentation tool does not seem to support builds (or animated Gifs), and I have had to use YouTube Videos as the video images (which is okay, as I derived them from there in the first place!). It gives you the gist. Oh, and the video for “We want to see…” is missing 🙁
See if you can make up your own narrative for the assembly.