What version of this game is this? Looks like there is a Japanese version and two different World ones. Interestingly it looks like one of the World versions has a note by a speedrunner that it is "the worst combination for the game".
https://www.speedrun.com/nemo_arcade?h=Deathless_All_Difficulties-Energy_Bars-Regions-Hardest_Very_Difficult-Minimum-World_901109&x=7dg3mz7k-ylpqdo68.12v6g9vq-0nw0z40l.1py3ree1-789d703n.qznrog4q
Looks like 2 Player mode has longer bosses aka more health, which might explain why every 2 player run is longer than their equivalent 1 Player run.
As far the tas goes I like seeing 2 players move around, but I do not feel that they are fully utilized as much as they could be. Also it looks like there is some kind of super powerup where the character gets red, but I do not see that being used as much as I would expect? According to wiki "Collecting a yashichi grants the player limited super attacks that fire a projectile and deliver more damage." Also at points it looks like there are unnecessary delays moving forward like right after 4:50 where one character was ahead but then it becomes nearly neck and neck with the other one.