Yes, extension increasing the angle, flexion decreasing the angle.
If I can request, don't "look" at Freddie or anyone else doing it (especially a static still, when both extension and flexion describe dynamic movements)...stand up and put your flat hand on your rear leg/hip (along the inguinal line), and move your legs/hips in simulating what you'd do with them in a swing a couple times, and then put your hand on your lead leg/hip (along the inguinal line), and do the same thing.
When I do it, I do feel the rear joint angle increase (extension)...and when my hand is on my lead leg/hip line, I can feel my symphysis pubis bone move closer to my lead leg/hip, decreasing the angle of that lead joint (flexion).
Those two things can also be felt or described as "external rotation" of the rear leg, and "internal rotation" of the lead leg if their respective feet were off the ground..."open chained", instead of "closed chain" as they are now. Is that of any help, or confuse things more?
I'm not confused really.
If you go by the textbook definition, both hips are extending/extended. "Extension occurs in the sagittal plane about a frontal axis" that's from physio-pedia. I did your exercises and they reinforced whats in the textbooks. No surprise there.
And yes I appreciate the discussion Mud(very much). I think you are wrong about Freddies hip not being extended. However, I think you were correct in saying There is more extension in the rear than the front. Even in freddie. Which is due to the femurs not being lined up like the weightlifter.
Freddie has very good hip extension in both hips. Because his femurs are pretty close to "the ideal" position (weightlifter). There are other players who have less efficient hips(hi level players!). If you guys remember when Shawn posted Pete Incaviglia, his femurs were so far askew he ended up with a lot of flexion still in his front hip. That Florida player gif that was floating around also had terrible efficiency with her hips(not saying she wasn't a beast of a hitter, Because she was!).
Now if you look at bonds and rendon...how they cheat that back knee instead of peeling it. That move gets them closer to the femur together ideal position very early. It takes a lot of timing of the rear leg out, because its already there. They're ready to send the bat and extend hips.
That's my theory.
And I dont think that bonds move is good for anyone but a big, strong, mobile, mature, hitter. The peel is much better/easier/safer for most imo. Plenty of examples of the peel nothing wrong with it. Cabrera and Bustos come to mind (two of the best ever) and many more.