It's documentaries about things like aliens and time travel. It's so easy with those topics to fall into the trap of saying things the viewer wants to hear. It's easy to say "Yeah aliens exist" for most of the documentary, but only mention how extremely unlikely it is once or twice. Take the viewer on some fantasy trip.

It's just my personal preference that I find with documentaries. I imagine that I'm in the minority to be honest, I think most people would like that kind of documentary.

One person who falls into that trap a lot (even though I think he's ace) is Michio Kaku.

That and action. Documentaries should have a little action as possible, unless completely justified. So many documentaries about the big bang have been ruined by having a CGI explosion every five minutes to represent the big bang (which is just as misleading as anything else too).

Luckily BBC understand this very well, and that's why they are the best at making documentaries lol.

Yeah, i know what you mean about that.. like travelling at the speed of light on the train, or how orbiting a super massive black hole will slow time down. but tbh honest these are the types of things that will interest people, the idea of exciting things like aliens will interest the general viewer who dosent have much insight in these things.

which is what i think he wants to do, because science is considered difficult by the general public.

sadly i'm not well versed in physics or mathematics, so i'm not sure who Michio Kaku is, but i know what you mean the bbc ones are very good in that respect, the Brian Cox one was very, very good. hopefully they continue it next year.

i recommend watching this: http://www.bbc.co.uk/programmes/b00vdkmj

it was on just recently about what some scientists believe happened before the big bang. quite possibly the best one i've seen, the end part was really interesting!!

Ones I would recommend, Sorta alphabetical

Blue Gold (2009) - Described by another poster above. 

Countdown to Zero (2010) - One sided but very compelling case for nuclear disarmament. Regardless of your political ideology this is worth watching.

Cove, The (2009) - Eye-opening documentary about Dolphins and this one particular town in Japan. I don't want to spoil anything, but this is a must watch if you like investigative journalism. 

Crude (2009) - Good overview on massive ecological damage caused by Texaco/Chevron in Ecuador. This documentary covers a heated class action suit waged against Chevron by the citizens of Ecuador. People are getting sick and dying because of Texaco operations while Chevron doesn't want to take responsibility for their actions. Well balanced coverage of the issue.

End of the Line, The (2009) -About overfishing, resource depletion and fisheries sustainability. An important issue that needs more exposure. 

Power of Nightmares, The (2004) - 3 Part BBC Documentary about the use of fear in politics. The first part of this documentary is a must watch as it shows the links between the early neo-conservative movement in the US and the growth of Islamic fundamentalism. Available for free on Google Video.

Sharkwater (2006) - About the poaching of sharks, mostly for Chinese people who are increasingly demanding Sharkfin. As more and more Chinese people gain wealth, they can afford and demand luxuries such as Sharkfin soup, where its consumption was once restricted to a very small percentage of the population. This documentary covers the devastating effects on shark populations worldwide as well as the highly lucrative sharkfin trade.

Planet Earth and Life are also great.

Michael Moore has a lot of good documentaries.

He also bends the truth.

Yeah, I actually watched that particular documentary twice. It was very good. Actually I mentioned it earlier in this thread.

Horizon has a great way of making almost any topic very interesting.There are some good one's from the past few series that may be worth tracking down if you liked that one, 'Who's afraid of a big black hole' and 'How long is a piece of string?'

I must have missed it when it was mentioned, but it was excellent.

I will check out those documentaries youve just mentioned when i have more time, the Horizon ones are very good. the Dispatches ones are also very good sometimes because of the focus on controversal issues like immigration, or racisim.