Re-enabled MediaRecorder in server_video.py, no output file is written

[HoustonHuff]

I've changed line 227 of server_video.py to "recorder = MediaRecorder(args.record_to)" to re-enable output file writing, but after an as far as I can tell successful stream, the given output file is never created; the stream ends, I hit "Stop" afterwards, I give the system a bit of time to work, and eventually terminate the idle server when nothing ever appears. I know MediaRecorder is doing something, though, as it needs the correct format of record-to to not crash, it just won't output.