The two great quality indicators of video making is lighting and sound and sound is one of the most neglected aspects when making a video. Perhaps you think that there is nothing you can do about background noise or a hissy soundtrack and that you will just have to learn to live with it - Not so.
Removing hiss and background noise is quite straighforward and easy to do with an excellent (yet free) program called Audacity. And this one simple process will do wonders in increasing the percieved quality of your videos. It's quick, simple and it works. This video will show you how - Check it out.