Replays: Advanced control of the camera

I like to look at my replays in World Of Tanks , but I have seen on many videos that the camera isn't locked onto a tank's view, but it can move as the player wants. I have only managed to change between tanks, not just move the camera wherever I want. Just look at this screenshot from a video I looked at:

The player is replaying the tank in the blue shape, even though he is looking from the spot where the camera thing is (in the red shape). The brown shape at the bottom right is there so you can't see the players account name.

So my question is, how can I do this?

There is no way to do this in the standard client of World of Tanks when viewing replays. However, it is possible to use a mod to add this functionality.

The person who made the video you saw probably used such a mod.

One free camera mod can be found here