A few years ago I can recall making my first attempt to try and photograph a field of lighting bugs and it is my recollection that it was a rather dismal failure. Several weeks ago confronted with a bunch of active ones, I decided to make another attempt, utilizing an odd and comical technique that I experimented with shooting butterflies. As fortunately (for me) there is no video of this shoot (maybe unfortunately for you) I can describe the technique to the best of my ability prefacing it with if you feel like you look ridiculous doing it, you are probably doing it correctly.
But let me digress for a moment. The tough part about shooting lighting bugs is that you don't know where exactly they are. So if you try to use longer lenses, focusing is difficult. And the use of wide angle lenses rarely renders the field of glowing insects the way your eye sees it. The luminosity of the insect can vary and the further away they are the less actual light makes it to your camera. Also, they don't take direction very well, so timing their flashing right is also a factor.
In my early attempts I used a wide angle lens, something like a 10-24mm or 24-70mm usually in the 20-24 range and had my camera on a tripod for a 30 second exposure f2.8-4.0 at 3200 ISO with the focus on manual (closer to infinity). Like trying to photograph lightning, because you don't know exactly where or when it will strike, you leave the shutter of the camera open and you hope it all works out. Though I met with some success of some little trails, I still didn't feel like it captured the energy that lighting bugs make me feel.
My next attempt was to see where the light was and literally chase the insects around, hand held with the shutter open for 30 seconds. See the light, chase the bug; see the light chase the bug. Obviously the closer the bug, the bigger and brighter it appears. In some cases, it is only a few bugs that lit up several times that made it look as though there are more. I also made sure to expose for part of the 30 seconds elements of the sky catching a little ambiance and context.
Unorthodox techniques sometimes yield some interesting results. If your first try at capturing something is less than successful, do something different, as you never know what you may find.