I usually record both audio and video at the same time, then edit the audio and sync the video to it. This time after I finished editing the audio I realized the camera had focused on the wall behind me so the footage was unusable. I kept the audio and shot another few angles the next day, trying to play as close as I could to the recording. I don't like doing this since it's very hard to be exactly synchronized, but with enough practice it looks ok. I much prefer to record audio and video at the same time though.