I thought round bales was a rather recent invention. The bigger size of the round bales is the relatively recent development.
This video demonstrates how the driver has to stop while it ties a bale and dumps it. It is a good thing they had invented live (independent) PTO by this time.
This was the solution to avoid stopping. They added the conveyor on top to take the hay, or straw in this case, back to the windrow. According to comments, this did not work well in some conditions and some farmers removed the "hay return" and just stopped when it was finishing a bale.
This video gives some insight as to how the thing works. Looking at the bales produced confirms that the string is wrapped spirally across the bale. I still have no idea how the twine is knotted.
A demonstration at a farm show.
In this video you can see the twine tube go across the bale. The comments explain why, near the end, he had to get off the tractor and throw a handful of hay into the baler:
In this video you can see where the baler isn't taking the hay in right so I stop it and pull a lever to reverse it for a bit then start it forward and the hay goes in ok then. When the string arm drops the hay going in should carry the string on in to wrap the bale, sometimes there is no hay to take the string on in and none on the conveyer in the right area to start it to carry the string on in. Toward the last of the video you see me get off the tractor and toss something into the baler, that was just a little hay to catch the string and pull it on in to the roll of hay so it could wrap it. After I throw the hay in you can start to see the string moving out of the string holder on the right going up to the top of the baler and in.
At 0:30 is a big corn crib with an elevator set up. Skip to 5:19 for the machinery. At 7:00 is the silage wagon unloading technique of using forks where the tines are bent down 90-degrees from the handle. The "apron carrier" is shown at 9:16. I don't understand how the "stack silos" work. My understanding is the silage needs to be wrapped to seal out the oxygen.
Another farm show demo. This video has some closer views than the other farm show video. I'm again reminded that old equipment did not have safety shields and it took a maze of belts and pullies to make the machine work.
This video includes the old rake design of the bars being rigidly attached to the end wheels. A Roto 10 but the hay return was not visible because the videographer was focused on the rear where the bale was being made. Later he added a clip that partly shows the hay return.
Unlike a square baler that has a chute that can deliver bales to a trailing wagon, this baler can just drop them on the ground. So they had to invent machines to raise the bales to a wagon.