If you are wanting to track your paint strokes to a source clip then you will need to use the Stroke option, and not either of the Multistroke option which are not trackable.
Create your stroke on the first frame. Make the Stroke Duration long enough for your purposes. In your Stroke Controls, right click on the Center value and choose Modify with Tracker. Set up your tracker to track the shot and track it. Your paint stroke will now be locked to the tracker position.
(A lot easier than doing the same thing in Smoke!)
It's not clear to me how to connect the paint strokes to the tracker. I use a stroke/clone paint brush. If I choose 'modify with' there are three options: tracker position, tracker steady position and tracker unsteady position. Which one do I need? And can you describe how to set up the tracker. If I try to track in the modifiers fusion says 'warning render did not complete'.
Sorry, I should have explained in a bit more detail.
Firstly, make sure that you are going to be tracking the right paintstroke - note that Fusion automatically sets up a new stroke immediately after the last one you have painted. To avoid confusion, I tend to delete Stroke 2, but you don't have to.
Next select the Center Position in the Stroke Controls (for the correct stroke!), right-click and choose Modify with "Tracker position". This will create a Modifier tab, so got to that next.
Drag your track source video into the Tracker Source well right at the top of the Track controls. This tells the Paint tracker which node you want to track.
Making sure you are on the first frame that you want to track, adjust your tracker position using the onscreen control - I'm hoping you know how to do this. Choose the Track Forward from Current Time option to execute the track.
Your paint stroke will now be locked to the tracker position. You can offset it if necessary using the tracker's X and Y Offset sliders.
[Frans Suijs]"Excuse my ignorance but it looks like I can only adjust offset values numerically. I don't see any sliders. Is there a shortcut that I need to use to drag to another value?"
Check out the tutorial for the correct way of setting up a Clone version:
As you say, there are no sliders to adjust the Offset values there, although you could set up an Expression (Modify with Expression on the Center value) which would allow you to assign sliders to them.