Here is an example (with no audio) of putting an animated gif file on a prim. You have seen those sorts of images, perhaps with a little character that jumps up and down or runs, like the Sonic Hedgehog, or one of my favorites, the Hello Kitty writing in a notebook.
Through a service provided by Peregrine Salon, you can upload your animated gif–providing the file is not copyrighted or has a Creative Commons license that permits free use–and the file is created in what looks the series of animations separated into frames. Don’t worry about how it looks. Download the file to your computer; upload to SL for L10 and apply as a texture to any prim. In this video, you will see it on all sides of a cube or one side of a flattened cube.
When Peregrine Salon creates the texture from your gif file, it also gives you the animation script. Create a new script in the Contents tab of the SL editing window and replace the default script with the new one and save it. That’s it. Your image will animate. You can change the frames per second in the script, which is initially set at 8. On the cube, I change it to 3. On the flat prim I make in the video, I change it to 2.
What uses can you think of for your animation? Maybe a nice sign that attracts attention to a display of art or an item you are selling. Let’s not get carried away and make anything that is disorienting or that turns avatars away, but you decide.
The details of how to pick or create an animated gif that will work well are here.
Here is the original animated image.
Wandering 
