Thanks for posting this. I enjoyed watching the videos
In the first game, the Priestess focused on the Necromancer too early with far too little damage potential. Using Divine Intervention to rush was a terrible move as well. Teleport would have accomplished the same thing for less mana, but there was not a lot of point in attacking at that point anyway. The Priestess also would have been better off leading with the economy and didn't use the Battle Forge particularly efficiently. Overall the Necromancer had a much better game plan.
The second video was harder to follow, although the openings seemed more reasonable. Some of the followup decisions were questionable, but overall I felt like there was a bit better strategy than in the first game. The Warlock needed to do a better job of focus firing and probably should have considered playing another threat.
In terms of rules issues, Defend can't target a Skeletal Knight. It also looks like Adramelech healed from Vampirism when attacking a nonliving creature, which he shouldn't have. You may have commented those, but I don't speak German, so I couldn't tell.