I haven't had any issues adding them to my hubs.
You can very well use it.. that ads is from google and it will be there.. HP has no issue with it..
I've used some of them :) So, go ahead as long as they're related to your hub (I mean the video and not the ad).
You can definitely use them since the ads on youtube are also google's. In fact if you have a youtube account and a google adsense account you will be able to merge the two. So the ads on youtube video shouldn't be a problem.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.