Due to lack of considerations on media scalability and reuse, most selective encryption schemes previously proposed might be hard to meet challenging requirements with a certain level of security which are induced from the multi-layer based video technique, for example scalable video coding. As a reason of that, first we discuss security concerns on this issue and then analyze the existing selective encryption algorithms in a media scalability point of view. Secondly, we propose the dynamic load balancing strategy for re-adjusting protection strength of reconstructed media and suggest operational mode which can be more suitable for media reuse. Finally, we demonstrate scalable security mechanism's decryption overhead compared with decoding burden in time and effect of visual distortion through our designed simulation.