reply to hyde1
Re: Content Filtering What corporations do is use proxy servers that point attempted connections to banned addresses to a web page with a warning.
Or, in a more SOHO or residential setting, the "at-risk" PCs could be connected to a separate LAN or VLAN. Then, within the firewall settings, block their access to whatever IP block Youtube occupies.
Unsophisticated users can be thwarted by modifying their hosts file so Youtube points to 127.0.0.1, or to a server playing 24/7 the recorded speeches of the Wicked Witch of the West (you can choose which one).