You absolutely can sell a used CD/DVD without any worry. The fine print on the label amounts to a contact of adhesion, and furthermore it's void by statute:

"...the owner of a particular copy or phonorecord lawfully made under this title, or any person authorized by such owner, is entitled, without the authority of the copyright owner, to sell or otherwise dispose of the possession of that copy or phonorecord." 17 USC § 109(a).