Having retained the urn at Old Trafford last week, England took an unassailable 3-0 lead with one match remaining after Broad added to his first-innings five for 71 with six for 50 as Australia, chasing 299, were bowled out for 224.
He told Sky Sports Ashes: "It's amazing. I just found a rhythm at that end, I had the wind helping me get the ball moving away from the right-hander. I just wanted to be more aggressive, I think we lacked a bit of intensity in the middle and Cookie (captain Alastair Cook) threw me the ball said 'let's spice it up a bit'.
"Bres (Tim Bresnan) and I got a good partnership going, hitting the wicket as hard as we could. 'In' batsmen scored well but it was hard to start on there and once we got a wicket we could put pressure on the Australia batsmen."
England wrapped up victory after claiming the extra half-hour available at the end of the day, though indifferent light delayed the re-entry of Broad and fellow paceman James Anderson into the attack.
Broad said: "At the end there, we prayed for a little bit of sunshine and it worked well for us."
Captain Alastair Cook said of Broad's efforts: "It was a great spell, he turned the game on its head. I can't praise him enough, words can't really do it justice. When he gets it totally right like that he's very hard to play."
Nine of the wickets fell in an extended evening session after Australia openers Chris Rogers (49) and David Warner (71) had frustrated England with a partnership of 109.
And Cook said: "At 120 for one, Australia were batting very well and we didn't quite get right but the character and skill after tea was fantastic. Tim Bresnan tied it up at that end, we talk about bowling in partnerships and without him going at one an over, Broady couldn't have got those wickets."
Bresnan earlier blasted 45 runs, adding to Ian Bell's third century of the series to lift England to 330 in their second innings to set a testing victory target.
"We wanted to be up towards 300," said Cook. "Our lower order have scored runs and it's proved vital for us."
Nobody, though, has scored more than Bell, who is up to exactly 500 for the series after rescuing his side from 49 for three yesterday with an innings of 113.
"At 50 for three, he's come in and played an outstanding innings," said Cook. "He's in great form, he's fantastic to watch but he's got them in really gritty circumstances, he's had a fantastic series."
Cook's opposite number Michael Clarke was frustrated but paid tribute to England.
"I guess to only lose by 75 (74) runs, we can take some positives, but our batting and middle order wasn't good enough today," he said. "I don't want to take anything away from England. Stuart Broad was outstanding in both innings and what a century from Ian Bell.
"We should have got more in our first innings but it takes good execution with the ball and they made the first tough breakthrough getting Chris Rogers.
"I think it was a pretty good batting wicket once we got through the new ball. It was always going to be a tough chase but if we played like we did in Manchester we'd have had a good shot at winning a Test match.
"I think a few of us need some more runs. We'll be working our backsides off. There's a lot to play for at The Oval."