I have the same issue. I strongly suspect overheating.
The Task Manager didn't do that trick as it does for you. It's been intermittent for me and usually stops when I interact with it as you described. However, today after a lot of video processing over a couple hours, it's shaking
into a constant blur and won't stop at all. When I stop the video process for a while (i.e., minimize the app), it will stop. It will stop more quickly if I place my hands on the top/back of it, which feels notably hot, but not burn you hot (i.e., probably
60C, but I don't have a temperature monitor for the CPU, nor do I know that it's CPU temperature necessarily). Touching it will conduct heat away faster than ambient air, so I believe I'm effectively cooling it faster by holding the back of it. I started
blowing on the back as well, it would cool and then heat up, stop shaking and then start again, repeat until it finally cooled.
I've repeated this about 4 times consistently by maximizing and minimizing a video application. Not terribly scientific, but I think it's an overheating issue with one of the components. Could be video processor, cpu, memory, or the display itself. I
don't know, but I'd bet it's more related to video/gfx processing or the display since I minimized rather than closed the video application. So if the memory and cpu usage remained about the same, and the shaking would start and stop based on video/gfx processing,
that provides a pointer.
Anyway, try some form of external cooling