A remarkable number of films absolutely botch their opening moments by introducing way too much information/needless detail or by providing essential information in a clumsy fashion. The worst ever example in the movies was David Lynch’s Dune, which had such an incoherent opening narration that when it played in the cinema, audience members were given an explanatory handout sheet with their tickets (And it didn’t help. Very disappointing given the greatness of Frank Herbert’s book).
At the other end of the spectrum, In a Lonely Place (recommended here) takes less than 5 minutes to show who Bogart’s character is and what drives him, and you can’t help being pulled into the story by both lapels.
A television series that opens its story as well as any is Patrick McGoohan’s brilliant (if uneven and occasionally maddening), The Prisoner. I re-watched a number of these recently and greatly admire the creators for trusting the audience by using a 90 second opening with no dialogue. The images make clear what the series is about economically and cleverly. The next 90 seconds of the opening were substantially the same each week, but included some tailoring for the episode at hand. It’s an arresting and innovative way to begin telling a story and it has great background music as well.