Please take a look at this FAQ:
In particular my bet is that Content Type detection is sometimes providing the columns you're expecting to see but it isn't always being triggered, probably because there isn't always a high enough percentage of video files in the directory you're viewing.
(It could also be that Content Type detection is switching to a different format because of some other types of files and that format is removing the columns you want. Either way, the FAQ explains all you should need to set things up as you want them.)