I need help/advice with modding my Gemini MM1 mixer

[three33ds]

I want to do the mod in this video:



But I have trauma from failing to mod a PT01 with a start/stop button that led to breaking the whole turntable. I think I'm really bad with electronics.

The mod seems simple enough, but I'm not sure what he is doing at the following timestamps:

0:55 & 1:05

Can anyone explain these steps to me? Also, what is that blue wire he is using to test the connections? Where can I get wire like that or what is it called (what do I need to google to find it)?

Thanks a ton for checking out my post.