The first one is challenging to do when you've never done any soldering before.

I tried soldering desoldering three resistors off a circuit board once (1996 automobile instrument cluster) to replace them with leads and a larger single resistor mounted externally on its own heat sink. That was a disaster..ruined a trace. It turned out to be a five minute job for a TV repair man to repair the damaged trace with a jumper and get my new resistor on there. Yeah that was my first experience soldering. Doing these deans was my second.

Anyway,

I'm not exactly sure what he was doing on that particular one where he melted the deans. I didn't have to much trouble with it once I figured out I could just tin the one side that the wire goes to while the iron was heating the connector from the other side...and do similar when I was ready to actuall solder the wire on. My very first one was a real mess. I ended up redoing that one again once I was done with everything else.