Unless you made a lot of money, my guess is you don't need to do much with it. But there are people outside the U.S. who may want to apply to get a refund from the withholding but they would have to file a tax return. For most Youtubers, it probably isn't worth the hassle to go through it. The IRS is tremendously backed up right now so unless you had the expertise to file it electronically, you could be in a for a long wait (assuming you were eligible for a refund).