For videos, I bet it was .mkv they mentioned. mkv can have different codecs and different tracks, including audio and subtitles. I see it used often for tv and movies. I’m not sure if there’s disadvantages to it for general videos, like ones shot right from a camera.
I’ve been happy with .7z or .tar.* for file archiving and compression, but I don’t know the pros or cons of each. I think there’s room for different methods of compression though, so a standard format should be able to use multiple.
For font families, .otf seems good for realtime text rendering. Seems any newer standards are mostly targeted at graphic design.