This is sad news since it's already tough to get people to watch videos from YouTube newcomers that have low view counts. People are much more inclined to watch videos that already have high view counts displayed from more established or more popular YouTubers.
On top of that, for new YouTubers to get someone to subscribe to their channel AND watch videos all the whole way through - that's an even bigger challenge.
So, I'm sorry to hear that they changed things up on you in the middle of your application @rulesforrebels.
In regards to AmazonTube ... Google is supposedly the largest search engine on the net and then YouTube is the second largest search engine (most likely because it's own by Google). Your average person will go to Google or YouTube to find information.
Amazon on the other hand is a well known shopping platform - not an information hub.
So, I doubt Amazon will be able to convert enough people into thinking that they are now the go-to platform for video watching or for gathering non-consumer and sales information.
Amazon already tried to branch out by creating an Etsy like sub platform for handmade sellers. It was a good idea, but I doubt it put a big enough dent into Etsy in regards to healthy competition.