Audio Matters
Besides the visual part of the movie, the audio is also a potential candidate for optimization. There are many cases when significant improvements to audio quality can be achieved quickly. For instance, adjusting the volume to the right levels is a simple step. Very often while audio is being recorded, the last thing that comes to your mind is to adjust the volume of the microphone. But later, when you play the movie, the sound is either irritatingly loud, or impossible to hear, both of which are really unpleasant.
Audio in screencasts
If the quality of the audio is really poor and you are the narrator, it might turn easier to record it again then to repair it. Otherwise, there are many tricks for cleaning the audio, but often it is just not worth the effort. For instance one unpleasant artifact is hissing and the best way to remove it is to use special programs (e.g. Audacity) but this is really a step that is difficult for beginners.