This page has several movies of STT-MRAM dynamics:
The uniform-precession mode, and two non-uniform precession modes
A and B .
There is also a movie showing the switching instability of STT-MRAM (see J. Applied Physics 117, 17B710(2015)) -- it begins with nearly uniform precession, in which the unstable mode is present with small amplitude (so that one side is precessing with a larger amplitude than the other side).
The unstable mode amplitude increases exponentially -- the precession amplitude on the left decreases so it almost stops, while the amplitude on the right increases so much that the magnetization (initially pointing toward the viewer) is precessing in the plane of the screen and then precessing around the direction away from the viewer. (Color code: red is pointing toward you, purple is in plane, blue is pointing away from you.)
The video stops when there is a clear domain wall, with red on one side, blue on the other, to keep the movie file from being too large. After that, the domain wall moves to the left, so the entire system eventually becomes blue and the DW disappears at the left side.