Pretty much. It's still new tech and aren't exactly "mainstream" yet. But it'll get there! Characters who are familiar with actual TVs and monitors would definitely help jumpstart the development and make things move quicker as they would be coming in with more knowledge about the tech, so all that's left is application of what's available.

As for dunamis, attempts have been made but not a lot or with great success. Music is simpler since its only sound and the nature of crystals and rocks in general. As for completed crystals—this is honestly going to depend on how it's designed.

If it's just going to be like a crystal be used as a DVD-R and have things "written" into it, then yes it would work, but it might not be efficient long term. A completed crystal would also need to be used as an incomplete one would be too easily affected by the holder. There would need to be a way to harness the power of as few crystals as possible and still be able to store a lot of data into them. So for example, if we use crystals like DVD-R, the memories should be compressed like into *.rar files and then something else will be needed to decompress the data out of the crystals and be ready and displayed on a screen.

That's just one example/idea, though! There's bound to be other alternatives and other ways to use the crystals.