Okay, when i edit a video and split some footage, it leaves a mark how long the video was originally. But when i render, it renders that part too to a black. Just black. So i can see the clip, but after that i see maby minutes of a solid black.
I don't think you SPLIT a clip in AE, I think you TRIMMED a clip in AE. A split clip would make two layers of the clip, one with an out point at the point of the split, and one with an in point at the point of the split. When you trim a clip you change the in and out points.... and if you only have one trimmed layer, you will see the comp's background color and nothing else before the in point and after the out point.
If you're actually trying to EDIT in AE, you will find that it's a difficult process. AE isn't made for editing.
I also think you need to spend a little time looking at the AE tutorials here on the COW, plus the AE basics tutorials on videocopilot.