So a while ago when the game first came out I found a simple way to clear the camera of Niko so that it can be used for things like Machinima
All you do is press RB or R1 so that Niko takes cover on a wall or any other object, then press and hold the right thumb stick in. This should give you a camera view that you can control freely without Niko being in the way. Sorry if this is old I tried a search but its been disabled.
Anyways, consider this a christmas present.