Yes, both players need to have the mod installed. But I believe that only one can play as the troll, if you want that changed then you should contact the mod creator
1:19 I thought it would be funnier if he just didn't kiss the princess, because he has really bad teeth and that would be fucking disgusting, the back-of-the-head sprite was already done months prior to that animation being made
Also I think the jump softlock is most definitely an oversight, I believe some beefy cutscene animation is missing somehow, this will hopefully be fixed in 1.2