I have a little, inexpensive Bescor LED on-camera light. It says it is 6500K and comes with an amber filter to take that to 4300K. I will be doing run and gun B-roll shooting at a convention. Getting vendors in booths, folks sitting in seminars, folks milling around networking, that sort of thing. I imagine there will be fluorescents in the exhibit hall and seminar rooms. Would you shoot the B-roll with the daylight 6500K or put the supplied filter on and go 4300K? Or does it not really matter so long as I white balance every 10 seconds (slight exaggeration). Thanks for any input.
You always have to pay attention to two color axes: red-blue, and magenta-green. The overhead fluorescents are probably roughly daylight (cool whites,) though they could be roughly tungsten (warm whites.) If they appear to be warm whites, you will need to warm up your light a lot; It is possible the "amber" filter will work. So much for the red-blue axis. Assuming the overheads are 'daylight,' your LED is probably too blue by a bit. I'd tape on a 1/4 CTO to warm the light up slightly.
Consumer fluorescents all have a green spike. You therefore need to add green to your light to match the overheads. I'd bring along a couple of pieces of 1/4 plusgreen cut to size to tape over the light. Start with just one layer.
Now white balance to a gray card with a mix of overheads and your light. Ideally you'd want to play back a test shot on a good, large, color-critical monitor, but you probably won't have access to one. So you'll have to evaluate on the camera's tiny screen. Or by eye.
It's also possible the convention hall has some other type of overhead lighting. Equally, booths may have different lighting. In all cases, you want to make your little light match as closely as possible whatever is up there. If at all possible, go in a day before and shoot tests!
Since you are shooting b-roll, that suggests someone else is shooting the a-roll. Confer with that shooter. S/he is really the boss here.