Q Which is best, method 1 or 2
A method 1 is simpler and you can use width to control the number of columns anyway
Q Do I still need the -webkit- and -moz- prefixes?
A I find it works fine on most modern browsers without those but no harm in being on the safe side
Q I see you have an image in the video. How does that work?
A Just insert it normally. You'll find it works best with no align but some trial and error should make it clear. Large images shrink to fit the column width. Nice.