Here's Mesogog
Here's the last Monster-of-the-day in the Fortress
Here's maybe new footage of the Monster as seen on the Computer Monitor however after looking through things, I don't know whether it's new or not
Shots of scene   which could be new.
Here's definite Sentai footage
New   
Sentai  
New  
Sentai
New
Sentai
New
Sentai  



These shots   are something that I'm unsure about but I'm mostly unsure about the Black one. I'm kinda certain the Red one is Sentai.
However here is when it definitely goes back to Sentai



NOTE: All Sentai footage featuring Mesogog's last Monster-of-the-Day comes from Abaranger 48.