As an addition to Yoshazu's post and to directly answer your question, YouTube rank has a base rank of whatever rank the player has on the server, even though they can /nick and /vanish.

So if the player you are asking about (probably yourself) has the non-donor rank, you will not be able to open 5 star mystery boxes, and no, you don't have to spend additional money on MVP or MVP+ in order to gain the rank.