Motion: About networked devices and removable media
Be careful when adding media files from a remote server to your project. Although the Import button (and Import command) can access the contents of other computers on your network, dragging remote media to your project does not copy the source file to your computer. The media source file remains on the remote device. As a result, when that remote device becomes unavailable, the corresponding item in your project goes offline. Further, depending on the speed of your network, you may experience performance issues when using media files on other computers.
Ideally, copy all media files used in your project onto a device that’s physically connected to your computer. If you must use media from a networked storage device, ensure that the device is always mounted on your system and that you have a high-performance network.
This is especially true for media from removable devices, such as flash drives, DVDs, and removable hard disks that are frequently disconnected from your computer. Always copy media files from such media to your local computer.