Its the only way to use the F4 radar to get BVR kills against fighters in my experience, known about this for a while, but that video explains it really well. I have the buttons mapped for entering Boresight and the different aspects on a 4 way push hat (push to enter Boresight mode).
You can use this method in WVR as well, just put the piper on the enemy, no need to 'Jester context button long' to lock, you can fire as long as you keep the piper on the bandit through firing to the impact.
The F4 radar is a Fire Control Radar really just for guiding missiles onto targets rather than for building up a situational awareness as well, as in jets from the F-14 onwards, so you need to be guided on to the target (as accurately as possible) to use this method.
One thing that is pretty key to note, is that if you are being guided on by AWACS in the F-4, you will need to know the MAG Variation on the map at that current date and subtract/add to the BRA calls by the AWACS to be guided on accurately and have the enemy in the Boresight cone.
F-16/F-18/A-10 can access the Current MAG Variation from inside there cockpit displays for sure, maybe others, so I use one of them to check it when building missions. Its a sensible thing to have in the Mission briefing page.