"I’ve seen this kind of video system failure on a couple of older Macs, and in my case it was almost always tied to the GPU or heat. A temporary workaround that helped was forcing the system to use the integrated graphics and keeping the machine cooler with better airflow. Resetting NVRAM/SMC also bought me some time, but it was never a real fix.
Long term, the only stable solution for me was either a logic board repair or moving to an external display, which oddly reduced crashes. If the issue shows up mostly during video playback or editing, lowering resolution and avoiding heavy GPU tasks can help keep things usable.
While troubleshooting, I also avoided re-encoding videos directly on the Mac and did simple trims instead. For that,
https://www.movavi.com/learning-portal/free-video-cutter.html was useful since it let me handle basic video cuts without stressing the system further."
