My VLC video player gives strange behaviour these days. When playing video, there is only sound with black screen. I once though the video files were broken, but they can be viewed by using QuickTime. So, the problem must be in VLC.
I searched on the Web and didn't find exact issue I encountered. Then I found this post, but the solution didn't work for me and didn't make sense to me. However, the post remind me about preference settings, and I thought of there was a post I glanced mentioned about video card. Oh! I've changed my video card several weeks ago. It might be the cause! I looked into the ``Video Settings'' of preference menu, and unchecked the item named ``Accelerated video output (Overlay)''. It works! :-)