The importance of sound in video has been very poorly estimated. The creators of videos have taken a lot of trouble in producing a first class video but have neglected to make audio of equal quality. Audio is an important part of your video. It makes the video come alive and brings more meaning to it.
Sound will set the mood of a video. The viewer can be swayed by their emotions if audio accompanies the video. Silent video lacks the means to charge the viewer emotionally. Many people watch a video because it brings them emotionally. Think about a horror movie. Would it be as exciting and frightening without the sound effects? Probably it would not.
Bad audio will ruin a video and take away its purpose. It will also divert the attention of the viewer. Audio does evoke emotions and helps the viewer to get more involved in the film and what it is trying to say. If the audio is not good then the viewer may not watch the entire video. This is a waste of your effort and frustrating to the viewer. The video will be less effective and its purpose unclear.
How to improve your audio for your video: Do not use your built in microphones for your camera to make the audio for your video. A better way would be to have a separate audio device that can be positioned away from the camera. Your microphones should be separate from the device and use XLR inputs. Be sure you have good quality preamps. This is another reason to use a good portable audio device. Try to avoid using Automatic Gain Control.
Try to have a separate person who will be responsible for the audio, so that you can concentrate on the video. There are several techniques that an audio person will need and so you should have someone handling the audio who knows what they are doing or your video will sound less than professional.
It is very important to synchronize your audio and video. There is nothing worse than having a video running and having the audio lagging. It will make your whole video look unprofessional.
To improve audio on your video, especially if it is shot outside, you can consider making a voice over for the audio portion of the video and adding it when you have completed the visual part. To do this you should record in a small rented room or space, where there will be less echo and disturbance. Be as close to the microphone as possible, especially if you are speaking for a tutorial type of video.
From these points you will see that audio is important to videos and you should pay attention to the sound when you create a video. A professional sounding piece will impress your viewers. Sound will make or break your video and will determine the amount of real views you will receive. Bear in mind that the amount of views will also depend on viral or word of mouth marketing. YouTube specifically does rely on this form of marketing.