Today the Holy Father in his sermon for Palm Sunday, which is also this year’s World Youth Day celebration, made a reference to the pre-Conciliar liturgy for this same Sunday.
Expanding on Ps. 23, he spoke to the young people jamming St. Peter’s Square about how at the time of the procession for Palm Sunday the priest would stand before the closed door of the church and knock strongly upon it with the processional Cross. The door would open and they would enter. This is, for Benedict, an image of how Christ, with the wood of the Cross, with the force of His love opened the door between God and the world.
Benedict used this to teach how we must open the doors of our hearts to Christ. Even if the words of Scripture or the message of the Church leave you indifferent, at least open yourselves to Christ. Look at Christ who suffered for you and suffers with you.
To recap, the Pope used as a starting point something from the older form of Mass to enrich the understanding of thousands of young people.
From my perspective, I believe this generation will learn from Pope Benedict about the Liturgy, the way the previous generation learned about Theology of the Body from Pope John Paul II, and in general, about morality (i.e., Veritatis Splendor).
There are many things the average person has never been taught about the liturgy, which is why it is so horitzontal or community focused in many parishes. He'll not force any "horse" to drink, but will put the water trough before all where if they choose, they will have their fill.
It's also interesting that he would choose an example from the Old Mass, but not surprising considering the expected motu proprio.