“So shall My word be that goes forth from My mouth; It shall not return to Me void, But it shall accomplish what I please, And it shall prosper in the thing for which I sent it.”
Isaiah 55:11 NKJV

Maybe we just need to have more confidence and faith that God’s Word is alive and active and will accomplish His perfect will. You don’t have to beat a dead horse. Like Bill said, Jesus didn’t stand up and preach for 40 minutes every time he spoke. He went right to heart of the matter much of the time.

For us, a big issue is we try to tackle to much ever time. So not only is the sermon long, but chance are it was too much for most folks to digest at once too. I think a big key is having a razor edge focus. Notice that many of Jesus’ parables are short and hit home quickly with the point. Yes, there’s times when he preaches for long periods of times, but I still think that it was many bite sized pieces.

maybe its: can we accomplish what we need to accomplish in less time?

The first issue would be the tension between the culture/reality of the physical world (a dynamic sermon preached in a physical place at a specific time) and the culture/reality of the internet (a sermon in a static place to be accessed any time). You sum up this tension with your statement that people will only pay attention to video online for 2.5 minutes while sermons last for 40. The solution to this attention gap is simple. Just let pastor Burke know that he needs to limit his sermons to 2.5 minutes. Problem solved. On the other hand you could just invest the time to edit the sermon down to 3 minutes with a link to the full sermon and help bridge the attention gap between the two cultures.

The second is your personal issue with the length of sermons in general (ever since your homiletics class). ‘Why does a sermon have to be longer than 20 minutes’ is akin to saying ‘why does a book have to be longer than 100 pages’ or ‘I don’t see why a movie should be longer than 60 minutes’. A good book, movie, or sermon needs to be however long it needs to be and engages us in a way that make the length irrelevant. A bad one, though, will make us say things like why did THIS book/movie/sermon have to be so long.

One final thought – people are precious, their time is precious, God’s Word (and the preaching of it) is much more precious.