The FSD birds did APG-66 systems integration, which was the standard configuration for Blocks 1 and 5 if I recall (distinguished with black radomes). YF-16s never had it because there isn’t any room, which is what he’s describing at 4:30. The first had a dummy HUD with a spin chute recovery system, then later installed the rudimentary Radar-cued optical gunsight where the HUD would eventually be installed in the FSD birds. If you look at the YF-16 cockpit variations, you can see the Rochester units with a flat top on the glass that distinguishes it from later HUDs with the curved top. The YF-16 “HUD” was really a gunsight with modes for the M61 and AIM-9s so you could have a captive employment envelope for AIM-9J, pulling the TGT into the seeker field of view with audible Sidewinder tone in your headset, then release the weapon once you heard the acquisition. APG-66 and later equipped F-16s had far more weapons-cueing capability and a truly functional working multi-mode pulse doppler Radar, which made the F-16A win multiple bombing competitions out of the gate in the early 1980s. The CCIP donut of death actually worked and allowed ease of bombing that was envied by all the strike-focused fighter communities. In 1985, F-16 units won six of top seven places in USAF GUNSMOKE '85 competition.