He is correct I have learned a couple extra facts Since making that video. Although in a well ventilated areas such as my Garage (where this was filmed) You have little to no need for a respirator while applying bondo, I have found through various research that it is in fact a producer of toxic fumes as well. They are more subtle than the resin, but they are just as powerful if you are not properly protected. ANYTIME you use the resin you must wear a respirator, and if you are not in an open well ventilated area you nut wear one for bondo as well.
P.S.
You should also wear a mask or respirator when sanding the mediums as both dusts are also toxic.