so you are taking other peoples clips, in YOUR montage but not claiming them as yours? What is the point of doing that if its your montage. But you could try to get premission from all of those fine montage makers and have a montage with thier clips and it would be mainly to practice your editing. But you wouldn't have it called "your" montage. You could just say these are the best clips of these people. Just an idea. May not even work. All i am trying to say is that i dont think it is a very good idea to do what some people were telling you.
BTW, good luck on your montage!