Agile Off Road has another good short video showing how the seal operates.
Cut the seal open and depending on the seals design there can be multiple sealing edges onto a polished surface or have a internal vertical face that seals. The issues with these type of seals occur at installation. Some seals can be separated and installed in two pieces with normal tools but there is a good chance the seal will leak after installation and leak worse if the sealing surfaces have been lubricated during reassembly. Some of these type of seals will have a special tool and or special instructions for installation to avoid distortion of the seal. The inner and outer surface that press onto the yoke and into the case may need sealant like Locktite 567 or 641 retaining compound to seal the two mounting surfaces to stop fluid weeping around the outside of the seal.
Depending on the internal sealing surface design these type of seals can handle pressure, they are used on some large engines accessory drives, industrial powertrains and compressors and in most cases are a better seal then a normal lip seal because when replaced the dynamic sealing surface is also replaced.
View: https://youtube.com/shorts/BxnC3pbznWc?si=3QuhMPtGOh_czJL9