It might help a bit but I do not think it will make a huge difference. I can see that it will reduce the bounce rate thus increase user experience when there are no advertisements, but if you have just a one banner, I do not think it will change much.
You can put an adult tube on the autopilot, I have never done that but your site will always require some type of work if you want to get good results.
Now, the video descriptions are not that important, but they sure can increase your rankings, but you surely will always need to add custom titles which are very crucial when it comes to the search engine optimization.