I sometimes hear sequences of fast (fairly random but in a general descending pattern) harmonics played on guitar and can't really figure out how it's done. I've tried tremolo picking the string while sliding over the frets with a light touch, but it doesn't really give the same result.
The clearest example I can think of is this song: (unfortunately, it happens at roughly the 1 minute mark, just as the video portion cuts out so we don't see what he actually plays...)
Edit: This 2nd video of a cover shows someone doing it without using the pick:
Any tips would be appreciated!