This is by far the single best (brief) explanation of Peak Oil I have come across yet.
Actually, the whole "Crash Course" is excellent. It takes a while to watch the whole thing, but I think it would work pretty well to cherry-pick the chapters that look interesting to you. You might miss some references, but they should stand alone fairly well. The more of it you watch, the more you'll understand my inner "doomer". This guy is really good at clearly explaining complex ideas, without talking down to anyone.
More to come on other topics, but that's all I have for the moment.