FrameLayout의 layout_gravity 설정

The layout_gravity attribute lands on the FrameLayout.LayoutParams, not on the view itself. You'll need something like:

mCameraPreview = new CameraPreview(this, recordMode);
FrameLayout preview = (FrameLayout) findViewById(R.id.camera_preview_wrapper);
FrameLayout.LayoutParams params = new FrameLayout.LayoutParams(
    FrameLayout.LayoutParams.WRAP_CONTENT, 
    FrameLayout.LayoutParams.WRAP_CONTENT, 
    Gravity.BOTTOM);
preview.addView(mCameraPreview, params);