From my understanding seeing this video years ago, it's a protest concerning a land grab made by the government. These men are farmers, and they protested selling their land to the government. Sort of like an eminent domain situation. What was the government going to do to the land? I don't know. I'm not even sure what year this was. It wasn't during President Park's era during the 60's and 70's, nor was it Chun's era in the 80's. This protest was much more recent, like after the year 2000.

These situations happen frequently in Korea. The government would grab farm land for various reasons. During the 60's and 70's, it was for the big Chaebols (giant Korean conglomerates) to build factories and office buildings. Keep in mind, most of Korea was an agrarian society after the war, and this was an attempt at forceful modernization. Most of the areas in the capital of Seoul was nothing but farmland, until the government starting building apartments and office space.

Here's an album documenting the modernization of Gangnam. Yes. That Gangnam. The same one from Psy's Gangnam Style song.

These land grabs keep happening, because of a lot of cities want to expand and bring more business. Poorer farmers sometimes welcome these changes, since the government will provide a substantial sum for the land, and maybe a free apartment if one is going to be built on the property. Other times, farmers will not sell their land, because it might have been in the family for many generations, or the co-op of farmers is somewhat successful or profitable.

The times when it gets really nasty is when the Korean government gives land to the U.S. military to expand military bases. The most recent occurrence was the expansion of Camp Humphreys in Pyeongtaek. The U.S. Army has been considering moving their bases away from the DMZ, and Seoul. The largest U.S. base in Korea is Yongsan Garrison in the capital city, and it's always been considered a prime target for artillery if the North Koreans ever attacked.

So the plan was to move the headquarters of the 8th Army down to Pyeongtaek at Camp Humphreys. One of the problems was that Camp Humphreys was not a large military base to begin with, so an expansion was needed to house the HQ, soldiers, and their families. The other problem was that farmland surrounded the base. So guess what happened? The government was pretty much forcing the farmers to sell. This enraged the farmers. Already there was tension, because farmers there couldn't raise livestock. The military vehicles would cause undue stress to animals living nearby. It also didn't help that Osan Air Base was next door frightening the animals with flight maneuvers. Needless to say, it got very nasty.

This video was supposedly shot in the 2000's. Right around the same time that the base realignments were announced. So I won't be surprised if this protest was related.

Edited: Spelling error. Thanks bodangren2.