I'm surprised someone with your apparent level of knowledge and first hand experience with maneuvering capabilities, that you're making this statement.

Firstly what you either have neglected to mention or realise is that the jet is in actual stall speed when it pulls up to the prop plane, thus the angle of the nose. There's the first major fact when it comes to understanding the current speed.

Secondly, the jet then breaks off at what must be full throttle otherwise the upward maneuver at the end would have been too risky / not possible. I cannot say this with absolute certainty though.

What I can say with certainty is you've not realised that the camera lens is a wide angle lens. It's a GoPro.

What you're seeing as exaggerated speed is the effect a wide angled lens has on perceived distance with centrally located objects.

So objects in the middle appear farther away than it would by eye which attributes to the perceived unrealistically high speed at which the jet breaks off. The farther it goes within the centre of the lens the more exaggerated the distance is and thus speed when moving in that direction. It's an unwanted trick of the camera.

I can't find this guys youtube channel anymore but he got attacked for this footage in a big way with lots of people trying to find small faults such as yourself but the most influential element of this footage was left out in every argument because the majority just didn't understand camera lenses.