jackau, if you are writting some essays for yourself, it's fine if you work using videos on the net as sources.
But if it's a "serious" essay. For the university etc... And if the people who will read it are actually history teachers who know their stuff... I would advice you to use books rather than videos. Unless you want a full presentation with videos and images.
My advice is to use books. And dont forget to quote your sources. If there is mistakes in your work, giving the sources will help a lot.
And try to understand the objectives of the people who make these videos. Do they want to inform? to sell the video?
And think about their angle. Are they talking about the soldiers? the political side of the conflict? the technological factor? etc...
I wish you good luck and "bon courage" in your work. And if you have enough time, do something really good. And show us your work if it's in english ^^
If you can show us you work before sending it to the teacher, we could give you some insight. ^^
And dont forget, knowledge is stocked in books. Not videos ^^