For something like this you don't want to use Camera Tracking. There are a couple of options. to stabilize the shot (not warp stabilize) by tracking a couple of points that will stay constant during the shot then do some roto work or clone stamp work to remove the hand and knee from the wall. Depending on what happens in the shot you may be able to remove the knee by exporting a frame as a Photoshop file and just painting out the knee. The hand, which I assume moves, will require some roto work and but you could probably do the same trick in Photoshop to paint in the wall and just use a simple roto of the actors back as a track matte to mask the fixed frame as the actor falls back in the frame. Your replacement background would look something like this:
You just need the part where the knee and hand are.
Now it's time to stabilize the footage. I'm guessing that the camera doesn't move a lot. You could either stabilize the actor choosing scale and rotation using points like like these:
Which would make the roto of the fall easier, or you could stabilize the camera move using points like this to stabilize the camera move:
Using either technique you will need to export a PSD file of the frame where you see the most wall. You might have to export more than one frame.
Once stabilized you would do your roto work using a technique like this:
NOTE: the technique that follows is a more efficient way to remove the stabilization than is shown in this video.
When the stabilization and the roto are complete you would add your replacement background plate to the shot, use the roto layer as a track matte for the replacement background, rename your stabilized footage "stabilized" so the expressions would not break, then add a null, apply this animation preset to the null and parent the track matte, the replacement background and the stabilized footage to the null to remove the stabilization from the shot and apply the tracking info, scale and rotation to the track matte and the replacement background. Your completed comp would look something like this (BTW, I only spent about 15 seconds painting out the hand and knee in Photoshop):
There is also a way to do this using Mocha AE to track and roto. The best option depends entirely on the shot.
The expressions used in the animation preset are:
x = value;
y = value;
tx = thisComp.layer("stabilized").transform.scale;
ty = thisComp.layer("stabilized").transform.scale;
nx = x/tx*x;
ny = y/ty*y;
Position and rotation are easy to understand. Scale simply divides the current value of the nulls scale by the scale of the stabilized layer to get the percentage of change and then multiplies that value by the scale of the null. Unfortunately you can't do division on array by simply writing value/thisComp.layer('stabilized").transform.scale * value because you can't multiply or divide an array by an array.
Thanks a lot Rick, I'll give this a go