Nice video you got there. Not many issue I would see. Audio can be hear clearly, music not too loud and overlap your voice and good editing skills. However, about the giveaway you are doing. Are you sure it a good idea for people to participate in the giveaway is to subscribe your channel? There will be people that subscribe just for the sake of the giveaway and if they don't they will unsubscribe. Subscribers will come along the way as long as you keep producing quality content video.