This post is more than 2 years old.
I'm a bit late on this as I didn't even know it was published yet (ok, just two hours ago, but still... ;) but today NetTuts published my video on Firefox DevTools:
It is a bit out of date (I recorded it a while ago) but that is mainly due to the fact that those damn Mozilla folks keep adding cool new stuff. Honestly, I've become so dependent on Chrome that I had not paid proper attention to Firefox or its dev tools and this video is a reaction to me discovering some of the cool stuff it has built in. I hope it encourages others to check it out as well.