Now on GameHistory.org, it's the Sega-Gremlin Marketing Archive!
https://gamehistory.org/sega-gremlin-archive/
This is a priceless collection of early-80s marketing videos from Sega Gremlin, most of them entirely new to the internet. This collection offers a rare glimpse at how arcade game makers sold their games to actual arcade distributors. Still images like flyers are easy to come by, but actual video like this is all but lost at this point.