For a good example of how important it is to get the sound of a video right, here is a video that at the time I write this has over one million hits.
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Notice in that video how it is basically a camera locked down and only showing a girls face....one million hits for a video of a face?
The reason this video is so popular is the use of sound.
To see this important and how it truly makes a video "pop", just turn the sound of your computer off and try to watch it......
Its too dull to watch without the sound.
The sound is not just the nice music, but mostly the voice-over narration that make this video worth one million views..
The voice-over narration makes the video appear more instructive, and more professional that just talking to the camera live would be.
Imagine how a similar voice-over narration might help a Bladesmith's video as he works on a new blade on a power hammer?