Swift has joined U2 and other musicians along with Universal Music, Sony Music, and Warner Music as a signatory of an open letter to Congress. The letter urges Congress to rewrite legislation used by YouTube and other web platforms that "threaten the continued viability of songwriters and record artists to survive." As Recode points out, the letter is technically asking for a rewrite of the 1998 Digital Millennium Copyright Act:
Technically, Swift and her co-signers are complaining about the Digital Millennium Copyright Act, the 1998 law that has governs the way big internet companies can use material uploaded by their users. But like other complaints about the DMCA that the industry has made this year, this one is really about YouTube.
In short: Musicians and companies that own music are complaining that Google's video site doesn't give them enough money for the use of their music, and that YouTube doesn't give them a real choice about whether and how their music is used. YouTube argues that it generates billions for the music industry (and that pirate sites don't pay bupkis) and that it has created sophisticated tools that make it easy for music owners to control their works.