Welll as a Larper, the first video is mainly cos-play.
Some of those pictures are Larpers but you can tell the difference.
There are only a few differences between what dagorhir or bel is and what most medieval Larps are. Those Larps usually have Magic, multitude of races, lighter combat, and a bit more math involved. In dag or bel you still have a persona you play when you fight even if you dont role-play. Also, Larps usually are a more social game involving a lot more talking and information gathering.
if you have any other q's just ask.