Yahoo tried to provide the regular consumer the YouTube user generated content model several years ago. I even worked on the automated UGC filtering for spam, adult content, and copyrighted materials for Yahoo at the time. Amazon will likely fair better here than Yahoo did, because they are pursuing the monetized content model and they know that model well from Kindle Direct Publishing and the Amazon Market Place. YouTube is driving further into this model with YouTube Red, so the market as a whole is going to grow exponentially.
It will be a tough road, but if anyone could compete directly with Google/YouTube it’s Amazon.