ffmpeg -i Slides_snip.mp4 -i AMIX_snip.mp4 -i "2016-03-06 20.33.55.jpg" -filter_complex "
[2:v] scale=s=hd1080, loop [background];
[0:v] setpts=PTS-STARTPTS, scale=w=960:h=-1 [slides];
[1:v] setpts=PTS-STARTPTS, scale=w=1240:h=-1 [speaker];
[background][speaker]        overlay=shortest=1:x=main_w-overlay_w:y=main_h-overlay_h [background+speaker];
[background+speaker][slides] overlay=shortest=1 [mix]
" -map "[mix]" -map "1:a" video.mp4

ffmpeg version 3.0 Copyright (c) 2000-2016 the FFmpeg developers
  built with Apple LLVM version 7.0.2 (clang-700.1.81)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/3.0 --enable-shared --enable-pthreads --enable-gpl --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-opencl --enable-libx264 --enable-libmp3lame --enable-libxvid --enable-libfaac --enable-nonfree --enable-vda
  libavutil      55. 17.103 / 55. 17.103
  libavcodec     57. 24.102 / 57. 24.102
  libavformat    57. 25.100 / 57. 25.100
  libavdevice    57.  0.101 / 57.  0.101
  libavfilter     6. 31.100 /  6. 31.100
  libavresample   3.  0.  0 /  3.  0.  0
  libswscale      4.  0.100 /  4.  0.100
  libswresample   2.  0.101 /  2.  0.101
  libpostproc    54.  0.100 / 54.  0.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'Slides_snip.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf56.25.101
  Duration: 00:00:10.01, start: 0.000000, bitrate: 919 kb/s
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709), 1440x1080 [SAR 1:1 DAR 4:3], 728 kb/s, 30 fps, 30 tbr, 19200 tbn, 50 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 250 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
Input #1, mov,mp4,m4a,3gp,3g2,mj2, from 'AMIX_snip.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf56.25.101
  Duration: 00:00:10.01, start: 0.000000, bitrate: 17736 kb/s
    Stream #1:0(und): Video: h264 (Constrained Baseline) (avc1 / 0x31637661), yuv420p, 1920x1080, 17552 kb/s, 29.97 fps, 29.97 tbr, 29970 tbn, 59.94 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #1:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 178 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
[mjpeg @ 0x7febda010600] Changing bps to 8
Input #2, image2, from '2016-03-06 20.33.55.jpg':
  Duration: 00:00:00.04, start: 0.000000, bitrate: 344973 kb/s
    Stream #2:0: Video: mjpeg, yuvj420p(pc, bt470bg/unknown/unknown), 3264x2448, 25 tbr, 25 tbn, 25 tbc
[AVFilterGraph @ 0x7febdc000940] No such filter: 'loop'
Error initializing complex filters.
Invalid argument