You need to figure out your threat model. Is it that you don't want YouTube to connect you to what you watch? Is it okay that YouTube knows that soneone at your IP watched the video? What about intermediaries knowing who you are or what you watch?
Most of these options just avoid using Youtube's UI, which at best blocks cookies, but reveal your IP. Others download, which is about the same.
I'd even recommend encryption for non-laptops, it's less about IF they get stolen and more about WHEN the hard disk fails, you don't need to worry about all of your personal data being immediately available to anyone who plugs in your failed disk (whether RMA'd or electronics disposal). Before diaposal, if you can, run
cryptserup eraseto scrub the encryption keys.