I'm wondering how do you guys play the music to the artists when shooting a music video. Obviously, headphones won't do the trick as you can't hide 'em What kind of equipment do you use?
I've had guys lip-sync to a boombox, and also just listen to the playback in-studio, but if you're on a larger set, you might want to take Dave's suggestion and rent/beg/borrow/steal a PA system so that everybody can hear and is on the same page.
If you have a lot of mobile/strolling shots, you'll probably need something smalller/portable, battery-powered, on a cart. Make sure it's loud enough, though.
Yup. The size of the PA is directly related to the amount of coverage needed for the set/location, but it doesn't take a fancy system.
There are other solutions, depending on the shot. Like Gregg, I've used a "boom box" before when it was a single artist. We were shooting on a labyrinth, and needed 360º of Glidecam coverage. I was able to tuck the system behind a rock so that it was out of sight of the camera. Also, I've done a walking shot from the back of a minivan (cheesy homage to Indigo Girls' "Closer to Fine" video). I just used the stereo system in my van as playback. The tail gate was up, and I was sitting on the edge with the Glidecam. For the original factory stereo system, it belted out plenty of sound for playback.