Use whatever song u want. As long as it isn't totally different it'll be ok. Like u don't want some heavy metal shouting song for a mini vid that goes kinda slowly or and incredibly slow song for a fast paced video. I'm working on my first mini video too but ive done A LOT of school projects where I have to make a video with music to go along with it. Please don't use that gay I Fought The War song. Everybody uses it and nobody who actually knows and studies music likes it.
