Those two videos show a Sony A7s camera hacked to record 4K video internally:
Sony cameras have an Android based system that allows the installation of apps from the PlayMemories store - this is probably what this hack is based on. Here is Nabil Fathi's description from YouTube:
"This is just a teaser of upcoming hack similar to magic lantern that will be available for the Sony a7a, possible on the a7s II but not sure yet. Higher bitrate, better subsampling (HDMI 10-bit 4:2:2), 4K recording, etc... (Do not misunderstand this part, what you see on the video, it is a simple port for fun, have a custom app that offer clearly more than that to come. This video doesn't show anything related to 4K, simply related to a7s access)."
