@obadiahjack
I ended up figuring out a round about solution, more details on this reddit thread for those looking:
https://www.reddit.com/r/RetroPie/comments/l51c9g/playing_video_before_shutdown/
My roundabout solution:
As discussed with reddit user u/ben_theredonit, the pi4 fails to utilize the emulationstation.sh at the time of posting when shutting down. So editing emulationstation.sh, will not work to play a video before shut down. I solved the problem through a roundabout solution. I found a shutdown button that can be added via the carousel, developed by Steve Smith. Below is his video and in his YouTube description, his files:
The user Lampros in the youtube comments has a guide to install, if you find yourself getting the permission denied error, as many people in the comments have, I fixed mine by simply typing "sudo" in front of the "chmod +x" command
From there, I simply changed the 'rom' shutdown script adding the "sudo omxplayer RetroPie/roms/shutdown/shutdown.mp4" code and it worked.
Big thanks to reddit user u/ben_theredonit, who offered their help.
I hope this helps anyone that was lost as I was when trying to add a shutdown video.