Feb 12, 2021
I recently bought a new laptop:

ASUS ROG Strix Scar 15 (2021) Gaming Laptop, 15.6" 300Hz IPS Type FHD, NVIDIA GeForce RTX 3080, AMD Ryzen 9 5900HX, 16GB DDR4, 1TB NVMe SSD, Opti-Mechanical Per-Key RGB Keyboard, Windows 10 Home, G533QS-DS96

And I noticed that when I play videos (windows media player), games (any), or even when I watch YouTube videos, occasionally the framerate will drop for a few seconds and the sound gets crunchy (like paulstretching or playing a video at 0.5x speed). In addition, after about an hour of use, this behavior stops, and things run normally, though it did lock up completely the other day playing a YouTube video. I updated my drivers, but I can't seem to find what could be causing this. Does anyone have any ideas?
The parts might downclocking from temperature. Laptops are small, so the cooling solution also has to be small. After it clocks down, the cooler catches up and brings things back to lower temperatures and the clocks can go up again. That could explain stutter in games and why it returns back. Not with video tho.

What are the temperatures while using it?

What do you mean with "an hour of use"? After you play/watch for an hour? After the machine is running for an hour?