Motocast is files that are shared between your PC and selected devices...these can be music, photos, documents...it keeps excess files off of your phone but the downside for wireless to work, both devices have to be connected to the network...
Info copied from Moto's website..
https://motorola-global-portal.custhelp.com/app/answers/prod_answer_detail/a_id/75576/p/1449,8119
MotoCast has two primary solutions that let you bring your music, photos, videos, and documents with you, wherever you go: MotoCast Wireless and MotoCast USB.
You can use one or both of these solutions based on how you want to access your media and files on your phone or tablet.
MotoCast Wireless
With this solution, you can stream your entire collection of music, photos, videos, and documents straight from your computer. There is no need to first upload your files to a public cloud, and no need to worry about running out of space on your device to store those files. Whether you are in another country, at the office, or in another room in your house, you can quickly and securely get access any file stored on your computer from your phone, tablet, or even another computer.
To use MotoCast Wireless, you will need to keep the computer you are streaming files from powered on and online. You will also need either a Wi-Fi or carrier data connection on your MotoCast Wireless supported device. To see a list of supported devices, please click
here.
MotoCast USB
With this solution, you can sync your music, photos, videos, podcasts, and contacts between your computer and your device using a USB cable. Any media that you choose to move to your device can be enjoyed even when you have no data connection. Any photos and videos that you capture on your device can be easily transferred back to your computer. The amount of media you can transfer to your device is only be limited by the amount of memory available on it.
With MotoCast USB, you can even update your device’s software. This feature is available to you as an alternative to updating your device over Wi-Fi or your carrier’s network. More information on Device Software Update in MotoCast USB can be found
here.
To use MotoCast USB, you will need a Motorola USB Cable and the computer where you store your media and contacts. For Device Software Update, you will also need an Internet connection on your computer.