It doesn’t look “random”. I think I saw some permanent structures and fixtures in that video. So, is this an illegal checkpoint? If a guy is travelling from one US town to another I would think it technically is. But I’m no expert.
A lot of people don’t know this, but during the depression California had border crossings with other states. They would not let you in unless you had proof of a waiting job, California citizenship, etc.
bump
They can ask but you don’t have to answer.
Also, make that between Laredo (Nuevo Laredo) and San Antonio. I noticed that Google, Bing, and Mapquest have removed the English names to US border towns with Mexico.
Laredo Tx is now Nuevo Laredo. The Texas town Brownsville is now Matamoros. Del Rio Tx is now Acuna, and El Paso, Tx is called only Juarez.