Louisiana has a teacher's union (in fact, it has two), but unlike in Northeastern states, they are not powerful at all when it comes to pay issues. They are primarily concerned with issues of teacher qualification and working conditions, but when a district pleads poverty, the unions can't get blood out of a turnip.
(The vast majority of rural Louisiana homeowners pay little to no property tax. The Homestead Exemption is $75K of fair market value. Even after Katrina drove up home prices, the typical house in Vermilion sells for around $105K, which means that the owner only pays taxes on about $30K. That's about $500/yr. Vermilion has about 50K households. This is why so many rural districts in Louisiana are heavily dependent on state funding to pay the bills, which is a problem, because the state economy is in the tank right now, and they are cutting education funding right and left. Note that Vermilion used to be quite rural, but in recent years has become partly suburban as the Lafayette metro area has grown.)
For those who are interested, here is Vermilion Parish's teacher salary schedule:
https://1.cdn.edl.io/FE8TlBQXhTc5ZO0uLROFo6l1fVdCO3PvIEJHw5NWPWYlfaeU.pdf FWIW, the "steps" near the top of the pay scale are largely theoretical; very few teachers are ever advanced to that level, and those who are are almost never women -- that level is mostly populated by winning football coaches. The "demand stipend" mentioned in the schedule is essentially hazard pay for those who work at the poorest schools in the district.
I know Vermilion fairly well; I grew up in the next-door parish. It's a pretty tight-knit place, and Colleen is absolutely correct; the Marshall would have been told in advance that any teacher who protested the Superintendent's salary increase was to be silenced and removed as quickly as possible. City Marshalls are officers of the court, but they have full LEO authority, which is why the deputy Marshall you saw in the video was armed and wearing a full equipment belt. Their normal duties are acting as bailiffs, prisoner transport and serving summons, but in some jurisdictions, particularly rural ones, they are often given much greater authority. Typically, the Marshall is an elected position and largely administrative, and there will be one or maybe two full-time Deputy Marshalls who are experienced LEOs; the part-time deputies normally have no more law enforcement training than a typical security guard, though most of them are military veterans and also serve in the National Guard.