Interesting evidence that hatred hurts itself
The IRA was very careful not to kill people, while inflicting plenty of damage on the British economy with huge truck bombs. Knowing that the British government and counterinsurgency people would want civilian casualties to mobilize public opinion against the IRA, they made sure to broadcast warnings to radio stations, newspapers, everybody, to keep the British government from gaining that success.
At the same time, the British were recruiting Protestant paramilitaries to murder Catholic civilians in Belfast in order to provoke the IRA to get into tit for tat revenge killings there, but the IRA disciplined themselves not to respond. Not at all because they were thinking of what Jesus said, I'm certain, they kept turning the other cheek in Belfast, never forgetting that their job was not avenge themselves or even Roman Catholic civilians but to convince Britain to walk away. And the way to do that was to keep blowing up billion dollar targets in London like the Stock Exchange, without killing people, while not letting the British draw everyone's attention to communal strife in Belfast.
By contrast Al-Qa'eda gave way to passion to kill people and burned themselves out.
I see one basic problem in his analysis, though. The IRA and Al-Qa'eda had very different goals, and in fact both have won in their own way. The IRA meant to get Britain out of Northern Ireland and to survive as a successful above-ground political party. Al-Qa'eda was not aiming to expel the Americans. On the contrary, its aim was to incite the Americans to invade Afghanistan and other Muslim countries in order to bleed out and collapse, as the Soviet Union did in Afghanistan before the Americans came to replace them, to the wonder of Russian generals. Al-Qa'eda didn't need to survive as an organization. It needed the Americans to invade and teach people that what Al-Qa'eda said about the invaders was true, so that the population would be mobilized against them. That's how Napoleon's empire was defeated in Spain and Russia, when regular armies could never defeat him. The American thirst for revenged has sucked in the Americans, having deprived them of their senses, just as Al-Qa'eda intended, and Al-Qa'eda was willing to lose its own life to achieve that win.
So both have won in their own way. From these two conflicts we learn that those who must avenge themselves will lose, and the winners are those who turn the other cheek, not being distracted from their goal by temptations to strike back. The one who lays down his life to attain his goal will win, and the one who aims to dominate in order to protect himself will bleed out and lose.
In the Proverbs we read that Wisdom shouts in the public square and at the head of every street. The Wisdom of God is proven true in the most unexpected events and places.