We acquired this video via Yahoo Japan auctions last month. It's a VHS tape that would've played on repeat in a video game store, showing gameplay from Chrono Trigger and Front Mission. The Chrono Trigger portion seems to have been recorded using the Prerelease build, or possible a build in between, as it contains the Prerelease version of the Lavos eruption sprite. The only other interesting part I caught was the exploration of Magus's Lair—the party finds Magus, but the battle doesn't start (obviously this event was disabled; can't recall if that's how it is in the Prerelease as well).
The most exciting find with this tape, however, is that it plays A Premonition, Chrono Trigger, Secret of the Forest, and Battle 1 as they would've originally sounded before downsampling/conversion to Super Famicom/SNES hardware. These versions are potentially how Yasunori Mitsuda and Nobuo Uematsu heard them before they were placed into the game. Check them out! Also check out the Front Mission video if you're a fan of that series; I sadly don't know enough about it.
Big thanks to Hidden Palace for alerting me to the auction.