I am following the VFX course the folks at FxHome have contributed to creating. Being impatient and wanting some things to play/work with, I did a simple Google and this is what I stumbled across. Google is your friend! I thought I would share this site in case anyone is interested. I link to a few specific pages but have a look around the site.
This page has downloads for tracking situations to work with.
This page has downloads for green screen keying work.
I've downloaded a few samples and they are typically larg(er) files since video media seems to be PNG image sequences.
The site also sells/rents a course and this page, shows some samples of the DVD videos. The samples provided actually provide some primo information on certain topics and DIY ways to help yourself set things up for post to work or work easier.