Well, I've watched them all and thought they were good and entertaining. They were especially exciting during the war.
I'm no master player by any means, but I have a few suggestions. You did a couple of things I would have tried to avoid. You fought a two front war for a long time. You had several good openings to make a great peace treaty with the purples. I keep my wars short, to the point and concise. Set a war goal, attain it with any means necessary, defend your own territory and then go for peace. I often even end up paying a few creadits to them for a peace deal, but that's acceptable, as long as I've gained my war goal. It's often when you start waging wars back and forth that you also start losing and the enemy sends in his landing parties to surprise locations.
You had your fleets running around from one end to the other and ending up in positions that weren't to your advantage. The automation created problems for you. You should set your fleets to be under full manual control. If I really want to keep a fleet in one position and be certain of it not moving anywhere, I usually put it in defenisve stance in the current system. In other areas, you would have done much, much better with more automation and less manual control though. I keep my automation in "Suggest" mode most of the time, because the AI does a pretty good job at suggesting locations where to build defensive bases, starports, sending spies and so on and that's usually what gets my empire going.
All-in-all I really enjoyed your videos. This game needs more Let's Plays on YouTube, and I've even been thinking of making my own, and then you'll get to hear me swear in irritation at the game too! I'm looking forward to more Distant Worlds from you. Thanks for sharing.