How are you accessing the MyCloud?
Using a media browser & DLNA?
Using a file browser?
The Twonky DLNA media server, by default, only presents media in Public.
http://community.wd.com/t5/WD-My-Cloud/FAQ-Twonky-DLNA-Media-Server-Setup-amp-Use/td-p/858810
This leads me to suspect you’re accessing via a file browser. If it’s able to bypass the share access control, WD should be made aware of it.
What model TV, and how is it connected?