Hi folks - wanted to share this here with hopes it may help someone. I use autohotkey extensively, and have developed a way to use video delay as an automated replay.

First the shortcuts that should be setup in vmix-
F9 - Save Video Delay to list
F8 - Next Item in list
F7 - Video List to Preview
F6 - Active Input

Here is the Autohotkey Script - You'll note that "sleep" after F9 is to allow enough time to save the delay - you may vary this. I have three F8's to make sure that I get to the end of the list.
Download AHK, create a new script, copy the text below between the asterisks, and run. Then press F12 (you can alter the script to match any letter shortcuts you have created)

********
F12::
send {F9}
sleep 6000
send {f8}
send {f8}
send {f8}
sleep 1000
send {f7}
send {f6}
*********



When F12 is pressed,

AHK will save the video replay to list, advance the list to the end, put replay video in preview, then send to active input, all automatically after pressing "F12". I then setup a trigger on the list video to fade back to camera 1 after showing replay.