If you use Windows for sure the system gets 'Paint' program. Open Paint and upload the picture. Open the folder where the picture is on your PC
Or 'Copy from' ...where the picture is
The picture has been uploaded
And now click the rectangle on the first row. Mark the area of the picture without black borders and cut it.
Reduce the area we left. Usually there is a blue point in the lower right corner of the area. Leave clicked the left key of the mouse and move it to reduce the area we will leave.
Later paste. Paint will paste what we cut before. And the picture is without black borders. Save the picture with that changes.
BTW, for music videos try to find the ones with better quality. From here
http://www.youtube.com/watch?v=csdOZXg-noA&feature=related you can get better and larger pictures. For instance
And do the same for the others contributions you have submitted. For music videos try to find the ones in HD. Add HD after singer + name of the song when you search on youtube and, perhaps, you'll find a music video with higher quality.