With just a touch of reluctance (and you can guess why), here is an edition of the "Capcom Games Guest Show" which featured the Mega Man Legends 3: Prototype Version. And, courtesy of the folks at Get Me Off the Moon, it even has subtitles (just click the CC button)!
My Nintendo News says that this is "unseen footage," though we thought we had posted this before (and cannot tell without conducting a thorough search). Regardless, the subtitles are new, so far as we know, so at least that balances it out somewhat if the footage itself isn't.
The YouTube description notes that this was aired "a full three months" before the game's cancellation, and "it is further proof that this product crafted by the hands of the fans is complete and taking up space on a hard drive."
And be sure to read the full description for a note from 100K's Jake Hans about how he believes marketing failed the project.
Thanks to Colonel Forte and My Nintendo News for the tip!