CameraCaptureUIVideoFormat enumeration

var value = Windows.Media.Capture.CameraCaptureUIVideoFormat.mp4;

// Captures a video using the specified settings.
function captureVideo() {
    var captureUI = new Windows.Media.Capture.CameraCaptureUI();
    captureUI.videoSettings.allowTrimming = true;
    captureUI.videoSettings.format = Windows.Media.Capture.CameraCaptureUIVideoFormat.wmv;
    captureUI.videoSettings.maxResolution = Windows.Media.Capture.CameraCaptureUIMaxVideoResolution.standardDefinition;
    captureUI.videoSettings.maxDurationInSeconds = 3;
    captureUI.captureFileAsync(Windows.Media.Capture.CameraCaptureUIMode.video).then(function (file) {
        if (file) {
            document.getElementById("message").innerHTML = "User captured a video."
        }
        else {
            document.getElementById("message").innerHTML = "User didn't capture a video."
        }
    });
}