Items must be created and in Draft status.
Go to Auctions & Items > Auctions.
Find and click your auction.
Click the blue Items button in the top right hand corner.
Tick the boxes next to the items you wish to add videos or documents to.
Click Bulk Edit.
Scroll to the end of the rows quickly by using the scroll button:
Click the icons in the Attachments column:
Drag and drop files into the Upload box, or click Choose Files to locate them on your computer.
Drag and drop YouTube links into the Uploads box, or copy and paste the URL into the box labelled "Paste or drop YouTube links here!" and press enter.
Once ready to upload, your items will appear in a list as shown below:
You will now see the icons in the Attachments column lit up identifying which media type is present for that item:
Click Save And Finish when you have finished uploading media to the items.
Change items back to Live status, if required.