If you are planning to film arc welding / Arc Brazing then DON'T! Not without shooting through a suitable welding mask. The amount of light from the arc is about the same as from the SUN! The UV levels if anything are higher. Using an arc for brazing while wearing short sleeves will lead to arc burn much faster than exposure to the sun, well compared to the sun of an exceptionally good English summer; I know this from personal experience. I would be inclined to start with the same amount of filtering even for gas welding, it is easy to then go the other way, rather than starting without the filter and trashing the sensor.
You can get welding mask filter glass, and it is quite easy to cut it to size to fit a Cokin style filter holder, the glass thickness is close enough for it to fit properly. This was the approach I used to try to photograph/view the Eclipse we had here in the UK about 10 years or so ago. Unfortunately the weather clouded over and all that happened was that it got dark in the middle of the day!
Alan