swap filename/format order

[coderofsalvation]

it seems that the movie-node has a hard time loading webcam/x11grab.
How to reproduce:

1. create movie node
2. enter filename /dev/video0 and format v4l2 or video4linux2 (see docs)
3. enter filename :0.0+100,200 format x11grab (see docs)

Usually hitting ctl+enter makes the output-socket appear, but here it displays error:

Failed to av_format_open_input <filename>
cannot init str for filter

looking at the docs, the fileformat should be passed to ffmpeg first, before passing the inputfile..perhaps that's happening in the reversed order?

[richardpl]

It does not work as libavdevice is not linked into binary at all currently.

[richardpl]

Look at latest change, It should work now, tested with pulse locally.