system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why my Laptop's Hardware runs hot when playing a mid quality flash movie in my browser but stays cool when I watch a DVD or a movie (e.g. avi) in VLC?
gpt
Flash playback and DVD playback are handled in two different ways by two different processes. Most Flash animations are not "hardware accelerated," which means that the CPU/GPU is not designed to handle those operations more efficiently. Because of this, Flash usually uses a lot of CPU cycles to render video/animation. This is a shortcoming of both Flash and Flash developers. More CPU cycles = more heat.

Most DVDs are encoded in MPEG2 for video, which has a substantially lower overhead due to the MPEG2 design. Modern CPUs and GPUs support MPEG2 hardware acceleration, meaning that they are optimized to decode and display the contents of a DVD (and anything else in that format). Since the CPU doesn't have to work as hard, it stays cooler.