It Used to Be
What's the first thing you would do when you think about an important purchase? You may ask your friends or relatives about the product. Ask them what was their purchase experience like or did the product meet their quality expectations? That only works if you have a relative or friend with the experience.
You will go online and start looking around. You might even go to Yelp, Google Plus or the ubiquitous YouTube to find out more info about your pending purchase.
What About You
What will people find out about your product or service? Online reviews are good and help with your SEO, but finding solid proof about your product or service is the goal. Being on YouTube or Yelp, explaining and building value is what you need. Today, sales representatives don't need to spend all their time talking about the features of their product they are selling.
In today's world, customers want to understand what they are buying, what the process is like, and will the product / service perform as expected, all backed by evidence.
Only video lets you show real examples, details of your product and the passion you have to do it correctly!