[Ammer Van de beering]

I know, my workflow is a bit messy.

I basically have a clip of a friend snowboarding downhill.
Now i want a clip from another friend to slide in from the side.
I just dont want the whole clip, just part of it.
I can do this with a mask, but the problem is, the friend in the second clip is moving around the screen, so i want to track him so he stays in the centre of the clip.

Once he is in the centre i want to use a mask to cut out all the excess footage.
Can someone help me with this?