The Blackmagic Video Assist is a versatile device that serves as a portable monitor, professional recorder, portable scope, and camera viewfinder. It can enhance any SDI or HDMI camera with better recording codecs and a larger display. Key features include built-in scopes, focus assist, a tally indicator, and 3D LUTs. The 3G models support up to 1080p60, while the 12G HDR models support up to 2160p60 and feature a brighter screen for HDR and outdoor shooting. The 12G HDR models also support Blackmagic RAW recording and use L-Series batteries for extended life. Essentially, it's four powerful tools in one.