> Found "Pidgin messenger" installed on my Ubuntu Studio. It purports to > talk AIM, Bonjour, Gadu-Gadu, Google Talk, Groupwise, ICQ, IRC, Simple, > Sametime, XMPP and Zephyr. No idea whether it does screencasts.
FWIW, I’ve had positive experiences with Jitsi: https://jitsi.org/ It requires a modern (>2013) browser as it works via WebRTC, platform-independent, open source (according to their website). Audio/video calls and screen sharing is available and works (tried on Ubuntu and Windows). Cheers, Joram
