I apologize in advance for sounding dense, but I must be missing something. Apparently you have a layout with Fastrack switches. In your initial post you link to a thread which discusses the so-called "yellow wire" which is an output signal from a Fastrack switch which can be used to determine the thru vs. divert position of the switch. As you show in your youtube video the Fastrack switch is a "modern" design with LEDs, diodes, etc. The Marx switch is an "old-school" design; it does not offer that same "yellow wire" output signal.
Question 1. So are you asking how to create this "yellow wire" signal from a Marx switch?
Question 2. Apparently the Marx switch is a one-off (all your other switches are Fastrack) and it's for use on a bench. If on a bench why is it important to have an indicator of which direction the switch is thrown? Seems to me if it's on a bench for testing purposes, aren't you're staring right at the switch so why the need for a direction indicator?
Question 3. You say your have an MTH 3-aspect signal head and you even show it in your video. I don't understand how a Red-Yellow-Green signal head, not to mention one with MTH's integral yellow-to-green timer, relates to your original requirement for a thru vs. diverge 2-aspect indicator. Do you use or plan to use a 3-aspect signal head to indicate switch direction on your layout?
Thanks for the reply Stan. Yes, I am wondering if I can create the yellow output signal on the marx switch (for testing so should I mess up the wiring I wouldn't damage an $80 fastrack switch). In response to question two, I want to mimic what the fastrack switch would do when the position on the switch is changed to thereby have the lights on the signal change as well. For question 3, I'd like to use that signal shown in my video to indicate the switch direction on my layout. Hope this helps.