Looking at /run/user/1000/xpra/:7.log I see: ffmpeg: h264+mp4 encoding failed: Success ffmpeg: vp8+webm encoding failed: Success ffmpeg: mpeg4+mp4 encoding failed: Success ffmpeg: mpeg1 encoding failed: Success ffmpeg: mpeg2 encoding failed: Success ffmpeg: all the codecs have failed! (h264+mp4, vp8+webm, mpeg4+mp4, mpeg1, mpeg2) automatic picture encoding enabled, also available: rgb24, rgb32