Fridndly word of caution
Never do Side Planks propping yourself on the palm of your Hand, you're bearing a lot of your bodyweight on the wrist and could damage it.
Side planks should mimic regular planks, by using the sides of the feet and the Forearms for support.
The raised Arm position is an optional thing and you could do side planks with the arm resting down the side of your Torso, but never rest on the one palm, as your wrist could be damaged by the weight stressing on it.
I mentioned this, as that 60 second P90X video shows it being done the way I said shouldn't be, as does one of your blog pictures and for your own safety, use the Forearm method.
You'll still get good elevation off the ground with the Obliques and Torso, doing that anyway , but using the Forearm will make what you're doing more safe and give the position more stability when you hold it