Our videographers don’t rely on the camera microphone.  We use Sennheiser wireless microphones to capture most of the audio and we also have small portable recorders that we can place  for even more ambient sound.  We prefer to place a wireless clip-on microphone on the groom and officiant to capture most of the audio at the ceremony. We use the same microphone to capture the best man’s speech at the reception if we are not able to get a feed directly from the DJ or band.