I would say WordPress now. Their new release has one click upgrades, and is dead simple. There are any number of YouTube plugins for it, making it dead simple to insert a YouTube video.
You can even make bookmarklets, so the YouTube page you are on, will get that video embedded into your blog, and you never leave YouTube. You can set it to auto post, or just sent to drafts. WordPress is much more ubiquitous, more supported at more ISP's, and has a much larger and more active community to it.
Joomla can do just as much as WordPress, and WordPress can do just as much as Joomla. I tend to go the path of least resistance, which I feel is WordPress. Joomla is a little newer, so the code may be more clean and manageable.
Wordpres is older, and had more time to have security issues vetted. Without knowing more about exactly what it is you want to do aside from the content you want to post, it is hard to give a good answer. So far, your feature list is a afternoon of WordPress tweaking, if not less.It will mostly depend on how you want it to look and how complex your design it.
Functionality wise, it is pretty simple, a few plugin's and you will be on your way.
Actually I think I read that Mahalo Answers uses MediaWiki.. and since this has a lot of the features you are looking for MediaWiki might work for your site also. mediawiki.org/wiki/MediaWiki Also, you could consider creating a YouTube Channel. google.com/support/youtube/bin/answer.py... I would guess that Joomla might have more options for customization, modules etc.And so it could be easier to adapt to your needs but I haven't customized WordPress or Joomla myself so I wouldn't be too sure.
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.