One way you could do it is to get an Capture Card (like an Elgato) and then Record it from your PC Screen.

Or is there a possibility to host a Game on a Windows computer or Mac and others can join? So i could just record my windows/mac screen to record the gamplay...? I tried to host a hgame with Project64 and the AQZ-Netplay Plugin but my retropi said: "implementations differs", when i tried to join the game with my retropie :/

Sorry to bump this, but does anyone know how to pass additional commandline options to ffmpeg via --recordconfig?

@herb_fargus to avoid this confusion I've just made a PR to explicitly use rgui as the menu_driver. https://github.com/RetroPie/RetroPie-Setup/pull/1674

Im trying to twitch with this guide: http://selsine.com/2016/10/17/how-to-live-stream-to-youtube-from-a-retropie/ but emulator run slow and very lag, turning the game unplayable. Anyone can run it smooth streaming via twitch? Using RPi3 and retroarch 4.2.

Just an update in case anybody was watching this (the original) post - I've finally published the guide... I hope that you find it helpful - please feel free to ask me any questions (as I've not had time to polish it quite as much as I'd like) Details are on the forum post here: https://retropie.org.uk/forum/topic/2394/how-to-guide-recording-live-gameplay-in-retropie-s-retroarch-emulators-natively-on-the-raspberry-pi-and-twitch-streaming A direct link to the guide is here: Recording Live Gameplay in RetroPie’s RetroArch Emulators Natively on the Raspberry Pi