There’s enough space to add some sound bars to the video to make it even clearer it has sound. They don’t need to be accurate, just moving.

Also, I haven’t tested but it seems like uploading an image might be required? If so, consider reading the metadata from the file and extracting the artwork, if there is any.

Finally, instead of a fixed colour background you could try making it the whole image, then have a “cutout” in the middle which spins. Might even be able to add some white overlays so it looks more like a vinyl.