Ordinary income is just that — money earned for the work you do. For songwriters, the money you earn from royalties is considered ordinary income. The tax rate you pay depends on how much you make, from as low as 10% of taxable earnings to as high as 39.6%.
Now for a bit of push-back on the general tone so far. We (and the panelists in the video) have mentioned how technology can create some dangerous grey areas when it comes to education — such as removing the vital social aspects of learning and of music practice in general, and also subjecting education to frameworks often designed by non-musicians or engineers lacking a diversity of musical knowledge, awareness, and respect (and thus unable to build tools that allow for all modes of musical expression).