To add to what GreyGhost has said, think of LOS as sideways movement of the other aircraft away from your nose (let's assume you are looking straight ahead).
In a tail chase or head on attack, there is no sideways movement of the bandit...it stays on your nose. But here, when the MiG-29 breaks, the MiG begins to move sideways, thereby changing its angle off your nose. The change of this angle is its LOS...and the faster this angle increases means its LOS is increasing.
This LOS change is not just a function of the MiG's rate of turn...the MiG's speed is also relevant since a hard turning (high rate of turn) but slow speed MiG will appear more stationary, particularly when viewed from longer distances.
LOS is all about relative displacement (changes in relative position). This means LOS is more an aspect issue than angle off. Large displacement means large LOS.
I think everybody can understand it intuitively, in the brain, sort of...
Especially with Grayghost's car intersection example.
I remember though, Pete talks about line of sight rate 30deg off the HUD (with respect to the turning mig-29).What does this mean, basically, 30degrees off the HUD?That 30degrees off the HUD, is what Pete describes as the "correct moment"
to start turning into the mig-29. The F-16 starts to turn into the mig-29, and maintains lag pursuit for a while... (until, gunshot opportunity is presented)
I mean, HUD basically just shows the main flight data. The HUD is an image reflecting equipment of a fighter aircraft, much like the reflector gunsights of old times in WW2.