Here are my screenshots from the TBS, Futaba, TEPCO 1, and TEPCO 4 cams during the event
It is a long pdf but has plenty of good screenshots for anyone interested in analyzing the event. Fog or smoke? Looked like smoke to me but I lack technical knowledge about visual effects of fog seen from a distance. The last few pages are scary looking until the event stops abruptly within a 10 minute period. I hope the dark effect is from layered fog rather than from thick smoke.