To capture video from my webcam I:

1. Use alsamixer to make sure the mic volume's on/up :)
2. Media > Open Capture Device (or Ctrl+c)
3. Make sure things are setup in Capture Mode, Video Device Name and Audio Device Name.
4. Instead of Play you want Capture

MIDI support is not included in the regular VLC package in Arch Linux. Supposedly it's included in the git version of the package in the AUR, but that's not currently building for me because of a Lua problem.