I grew up about 5 miles due East of Downtown Orange; it was one of my railfan hangouts for many years. One odd thing about the track arrangement back then was that it required a train to take a diverging route switch through Orange, in either direction, to stay on the 4th District main track !!! Look at the N/B San Diegan at the 6:20 time mark; it is taking the diverging route through the switch -- to stay on the 4th District Main Track. A straight route through the switch N/B would have put that train on the CTC Orange Siding; in this case after curving to the Northwest, the N/B train would then take the diverging route through the West end siding switch back onto the 4th District Main Track near Batavia St. crossing. I recall there was a scheduled daily meet between 2 San Diegans at Orange.
The S/B SDX train shown early in the video was going from the Olive District CTC Main Track to the Orange Siding, then straight through the South Orange Siding Switch onto the 4th District main Track. Not shown in the video was the North leg of the Orange Wye, running from the Orange Siding just East of Batavia St. to the Olive District Siding just South of Collins Ave.
Another interseting rail set - up in Orange was the Espee's Marlboro Spur, which branched off their old Tustin Branch and ran South parallel to the Santa Fe's Olive District from just North of Katella Ave., down into old Downtown Orange. There the Espee ( and PE before it ) served the East side of Santiago Orchards packing house, while Santa Fe served the West side of the same business !!! The Espee line was at one time known as PE's Orange Island after the 1938 flood took out the PE bridge over Santiago Creek between Orange & Santa Ana. The PE freight depot and a small run - around yard were still there, just North of Chapman Ave. at Lemon St. into the mid 1970's at least.