The black borders are caused by a mis-match between your Video and your Project's Preset.
Can you give us the full details of those Videos, such as where they came from, the Frame Size, the CODEC used, etc., and then the Project's Preset that you chose at New Project?
Also, see this article for more details: http://forums.adobe.com/message/3797172#3797172
Thanks! I think I found it by looking at the video. I knew my settings was wrong, but not where to change them. I opened a New project and selected the propper settings so start with now.
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When the Project Preset matches the Source Footage 100%, one should not have any black borders (unless they have applied an Effect like Crop), and there should also not be a red line of above the Clips, when dragged to the Timeline.
If things are now working for you, you might want to look over this article: http://forums.adobe.com/thread/1058744?tstart=0
Good luck, and happy editing,