Nothing will happen too seriously. The only one that has to worry is that one cop, and the only one that will get a token amount of money is maybe the girl that got ground into the grass. The gun being pulled is nothing, and while it looks bad to some, it still probably falls under justifiable use of force because at 3:08 or so, he is advanced upon by the two boys while attempting to detain the girl. All he'd need to do is express a reasonable fear that he might be assaulted, which should be easy to do in a pro law town like Texas.
If they can stick it out for a few days, he's home free, just a slap on the wrist.