What Youtube video on the My Cloud indicates you can “just plug my hard disk and watch my movies”?
The My Cloud is a network attached storage device (NAS). Think hard drive that all local network devices can access to copy data to/from and stream media from. The My Cloud must be connected to either your local network via the Ethernet cable/port or direct to your computer using the Ethernet cable/port.
If you haven’t already done so you should read through the My Cloud User Manual (http://www.wdc.com/wdproducts/library/?id=439&type=25) which explains the features/options of the My Cloud and how to use/access/configure those features and options.
Generally the way the My Cloud works, after one has connected the My Cloud to their local network and one has accessed the My Cloud Dashboard to configure the My Cloud, is to copy media (videos, pictures, audio) to the My Cloud using Windows File Explorer or Macintosh Finder. From there one can stream that media to other network devices that support DLNA, or one can stream just the music to iTunes enabled devices. Or one can use Windows File Explorer or Macintosh Finder to access the My Cloud and launch media files with their media player. It is recommended to “map” Shares to the local computer to make it easier to access the data stored on the My Cloud.
If you plan on copying your iTunes media library to the My Cloud make sure to copy all of the iTunes media library folders and to properly configure iTunes program so it points to the new media file library location. Do an internet search for direction on how to move an iTunes media library to an NAS drive like the My Cloud.
Lastly see the following link for more information on how to use the Twonky DLNA media server if using DLNA devices to stream media from the My Cloud on your local network.
https://community.wd.com/t/faq-twonky-dlna-media-server-setup-use/95373
