I didn't watch your video but here are some of my personal findings.
My machine is a '94 88HS
When batch sending to my machine it works best to have no line numbers in the file.
When DNC you need to have line numbers.
I found that I needed to add a "line pause" protocol in my batch sending software to keep the control from missing or skipping data during send, it is something like a .2 - .5 second pause per line.
I am also running a higher baud rate, I don't remember which off-hand but I think it is 19200 (just so you know that you can speed things up after you get the issues sorted out.
Other points of note; My cable is about 3X the length of yours and I am using a serial to USB converter. If anything these are negative aspects to my setup.
I have never needed/wanted to send a program back to my computer from the control so I have no insights there.
HTH
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