API control of video capture from host OS possible?

[jdesbonnet]

I'm liking this new Video Capture to webm video file feature in VirtualBox 4.3. However I cannot find any way to control this from the host OS. I'd like to have an application on the Host with a button to start/stop screen recording (and also control the location of the capture video file, but that's less important). I can't find any VBoxManage command options for this. Any help would be appreciated. Thanks!