Something that has always bothered me was the time it takes to render a 2d video. Now I've seen computers do some crazy things in real-time, but when it comes to video rendering, it's surprises me how slow it can be. I can understand why 3D rendering takes a long time, but when a computer renders a video isn't it just replacing the pixels of the original video in the background with the new ones you added?
More aboutvideo rendering questions
Yes, but video rendering is most usually done by the CPU, which isn't very fast when compared to GPUs (it's around 50 times slower).
Yes, the previews are handled in hardware, but generally the final rendering is done in software with the CPU.