Mixed rare earth garnet single crystal materials provide a unique environment for magnetic domain wall motion. In these materials, characterized by a low magnetization and a high anisotropy perpendicular to the plane, many wall structures seem possible, leading to a number of new and interesting modes of motion. A review of the wall motion as seen using a sampling optical microscope, capable of observing the dynamic domain configurations with a 10 nsec single exposure time, is presented with emphasis on the role of thevertical Bloch line. It is shown that the wall dynamics for bubbles in translation, overshoot and creep, is dominated by vertical wall twists, i.e., vertical Bloch Bloch line pairs of opposite twist direction. For walls driven by uniform fields, such as radial expansion and collapse, wall structures less well understood dominate the motion, resulting in different dynamic characteristics depending upon the specific drive conditions for the wall.