Greg, Matt's video is good value and I believe that was where I started from after getting frustrated reading Tony's tutorials. I then found Sean Bagshaw also goes into the detail of how to intersect / subtract masks but it is in his paid series of videos.
Like you've commented, I found it very useful learning the process and understanding how to create my own tailored masks, especially when I want to use just one of the colour channels rather than the combined RGB. Though for the most part I now use the Tony Kuyper panel that has the one button actions for the full range of RGB lights, darks, mids, individual colour channels, as well as two button actions that allow you to subtract light masks from light, and darks from darks. I find these especially useful to maintain contrast, so sometimes I want to keep just a few of my brightest highlights but bring the others back a little, so I will subtract a lights 5 from a lights 3 or 4 to protect the brightest but work on the others maintaining the feathering so no halos.
BTW I learned how to use the less obvious elements of the TK panel through Sean Bagshaw as I struggled to digest Tony's own tutorials. Up till getting the panel I'd built my own actions, but found value in getting the full panel in the end.
A couple of other freebies on the intersecting process I've found over time, though not all videos:
Hougaard Malan -
http://www.hougaardmalan.com/blog/ad...t-application/
Self-Intersecting Luminosity Masks at The Wonder of Light-
http://www.thewonderoflight.com/2011...inosity-masks/
BW Vision-
http://www.bwvision.com/luminosity-m...mediate-level/