Many of us know Fr. Mike Schmitz from his great youtube videos and dynamic speaking; he also has lead tens of thousands through the whole Bible, other hundreds of thousands started with him. This year he's even doing the Catechism in a year, which is just amazing. If you aren't familiar with some of his works, please do check him out...he's just a great communicator of God's mysteries.
In this video, Fr. Mike is sharing with the 2019 SEEK Conference (campus college students...huge conference: 17,000 in person and thousands more online) about the Mass. In this clip, he speaks directly to the ad orientem orientation. He gives a very succinct explanation.
If you would like to watch the whole talk, which is about how to "Pray the Mass Like Never Before," click on this link; it is an excellent talk.