INFORMATION FOR OTHERS:

The drag chain from eBay seller shinyempire (linked above) can NOT be opened up for laying cables. The sections unclip, however cables must be threaded through them. Now I've got the dilemma of whether to buy another type of chain (and hope I can lay my VGA cable inside it) or cut the plug off the VGA cable, thread it through and solder on a new plug. Not happy.