It’s not illegal to scan currency (at least in the US), although the government requires companies like adobe to put code in their software to prevent people from scanning it. The images themselves are of course public domain. The US treasury department once had a site up where they posted some images of currency that artists can use in their work, though I dont recall the url.
The best way would probably be to just use an image of one. There are a number of high quality photos of the moon on Google Image Search, just be careful about violating copyrights.
Make sure you set the actual image sequence to 60fps. You have to rightclick it and go through interpret footage. I think they default to 30fps, so that would cause the problem you are describing.