If your audio is not in sync with your video you may need to delay your video. With the Video Delay filter you are able to delay video frames on a frame duration base. The filter preview will show on the left the current video frame and on the right the delayed video frame. below there is a representation of all video frames currently buffered.
To learn more about how to use this Video Delay filter in order to bring audio and video back in sync read the detailed description of the Audio Sync Meter layer.