Linux
Using jack audio / 1080p in webm. You need gstreamer.

gst-launch-0.10 -e jackaudiosrc connect=0  ! queue ! audio/x-raw-float, channels=2 ! audioconvert ! queue ! audiorate ! queue ! vorbisenc max-bitrate=128000 ! webmmux. ximagesrc use-damage=0 ! queue ! videoscale ! queue ! video/x-raw-rgb,width=1920,height=1080,framerate=30/1 ! queue ! ffmpegcolorspace ! queue ! videorate ! queue ! vp8enc threads=4 quality=10 speed=7 ! queue ! webmmux name="webmmux" ! queue ! filesink location=screendesktop.webm

With a gui:
https://github.com/MaartenBaert/ssr

Mac
Using Quicktime player

Windows
If anyone have a free solution...
Here's what I am using in the meantime:
https://screencast-o-matic.com