Where Can I locate the Record ID?

After you have uploaded MultiMedia content - a Record ID will be assigned to that content.

You will be able to see the Record ID located on the top right hand corner of MultiMedia Content 

by clicking on the image, video, audio, or document; you will see in the url that there is an ID=XXXXX -

those last numbers are the Record ID for the MultiMedia Content that you have uploaded into MediaWire.