The red arrow is where Officer Murphy crossed Stemmons from east to west, in Bell's footage.The distance tween Hoffman's Lookout & Murphy when on the western side is now only 33 yd.
But Hoffman says that Hoffman ran north (from Hoffman's Lookout) towards Officer Brown on duty high up on the railroad overpass 100 yd away.Why didnt he run to the 6 or so Officers below the railroad overpass at road level blocking traffic.
And what about Officer Murphy now only 33 yd south of Hoffman's Lookout & now on the same (western) side of Stemmons.
Hoffman was definitely on the Stemmons overpass on that day, & he must have been aware of all of the police present, yet in later years he forgets & comes up with a silly story.
Hoffman was definitely soft in the head. Its elementary.

As can be seen Officer Murphy while at the eastern barrier had a good view of the paling fence & carpark.
And he was a little closer to the carpark than Hoffman Lookout (which is on the western side of 5 lanes)(now 7).
Murphy was 196 yd from the fence, Hoffman's Lookout 217 yd, ie 21 yd further.And the large overhead signage that partly blocked Murphy's view of the triple overpass didn't affect Murphy's view of the fence & carpark.
I didn't draw Murphy's sight-line to the paling fence on the aerial, but it passes well clear north of the large concrete pillar at the north west end of the triple underpass.
So, if Hoffman saw 2 guys playing toss the rifle then Murphy would have seen them too. And the 3 guys that we see in some of the pix in this thread standing against the
north eastern concrete splayed retaining wall of the triple overpass would have seen too, the wall meets
the paling fence at about 45 deg, hence the 3 could see well into the carpark, & the 3 were only 12 yd from the fence.
And when the tossee walked out to the cabinet & disassembled the rifle
everybody on the triple underpass would have seen.