Actually, during that video Pete explains that mentality of that post-run routine should not be to "stretch", but more to "loosen". Basically, you're just trying to undo all the little muscle spasms that were caused during the workout.
I think I was overstretching before hearing that, so what you're saying makes sense to me in that way.
OP - one other thing I recently started doing just before a run if my calves are a little tight is a self-massage in the calf. In a seated position, rest your left ankle over your right kneee. Your left calf will be right in front of you, and completely relaxed. Now, with your thumbs and fingers dig in deeply into the calf muscle, and really work the muscle. Just 20-30 seconds of that often does the trick for me.