What is said on YouTube does matter. In the case of Norman Leboon, his YouTube comments and threats led to his arrest:
“U.S. authorities have arrested and charged a man with threatening to kill the No. 2 Republican in the House of Representatives, Eric Cantor, and his family, according to court documents filed on Monday.
Norman Leboon, 38, was accused of making the threat in a video on YouTube in which he said, “You receive my bullets in your office, remember they will be placed in your heads,” according to an FBI affidavit accompanying the charge.”
This example may be an extreme case. However, it does serve to illustrate that online activities do have consequences. An online threat is not an expression of free speech. It may be a precursor to a visit from law enforcement.