HN39, it helps to view the image in message
1340. The velocity of the plane at an angle of 45 degrees (ignoring wind) is about 151-152 knots. The fuselage is at a 61 degree angle to the flight path. Take the cosine of 61 degrees and multiply it by the velocity and you get something on the order of 73 knots. Now it's easier to entertain the notion the 132 knot velocity component across the inlet to the pitot would have it reading "somewhat" low.
The image in 1172 has a misfeature. It implies you can take the cosine of 61 degrees and multiply it by the horizontal velocity component and get something meaningful. Note that the vertical velocity rotated to the plane's reference gives a rearward velocity that subtracts from what you computed.
It's, of course, all quibbling to show that poor pitot had ample reason to read incorrectly.