its kinda hard to explain but the little green bar above the timeline means that part of the video is loaded right? but it never goes through the whole video so i struggle to edit because when i scroll i have to load each frame individually , how do i make them all load? thanks
To expand on Mylenium's answer a bit, AE is in NO way an editing application like Premiere Pro, FCP, Avid etc. It was designed for entirely different things. It's an effects, compositing and motion graphics application. That's what it does. You don't use it to arrange video clips in a desired order, trim clips, and play back the result as you would in a video editing application. It has NEVER been able to work in real time.