Disclosure: Long term filmer here, not so much in the past few years, but I've been slowly working on a new video.
As for being drunk / stoned, it is a method but it makes it a lot tougher to stay on top of footage, making backups, not missing the shot, and actually giving a shit about the trick the skater is done. I've been a lot more productive as a filmer when I'm not fucking with alcohol or getting stoney baloney. It also comes out in the editing, more killer, less filler.
One thing to realize is a large majority of filmers are doing it as more of a creative endeavor, and not a business one. Perhaps that has changed, but if the passion to document isn't there, you should probably put the camera down and skate. Skaters can tell whether or not you are into their trick. Needless to say, I've reached a breaking point where filming your typical skater doing a typical trick down a typical obstacle is almost torture.
Creativity, style, and flow outweigh the boring robot shit. If you are a skater and are subconsciously forcing your filmer to stand in one place for hours on end while you try to learn a trick, that shit is whack. Move on and do something you can bang out in a few tries. It will look better. Think Tommy Guerrero skating down the street versus some one jumping down a set of stairs for hours on end. Which filmer do you think had more fun in the process?
I could rant for hours on this shit, but these days I'm more interested in documenting skateboarding where the skater is pushing themselves in a natural trick selection. Not trying to conform to a style or process.