I feel it when I hold it on my legs.
Historically, that's a major cause of overheating in laptop computers regardless of make.
The M4 14" has cool air intakes low on each side where the bottom plate meets the main chassis:

Chances are high that using it in your lap is blocking cool air from getting in to some degree. Also, hot air is expelled through the hinge area on the back. Do not block that area. See:
Keep your Mac laptop within acceptable operating temperatures - Apple Support
Watching videos is one of the highest-demand tasks you can do. It will run up temps even with all vents unobstructed, but should remain in safe ranges. Be it in a game, a streaming video, or video-conferencing, it works the CPU and GPU quite hard.
I'm not saying don't watch videos. I'm saying make sure your computer can breathe without restriction while doing so. If you must hold the computer in your lap, get a rigid lapboard. I even used one of Mrs AJ's larger plastic cutting boards for a lapboard (please don't tell her!).