For those video files that DOpus can calculate, you have to give it time to work out what is going on. How long it takes depends on the number of files involved. And video files are big, so need time.
Not all video files work. Just AVI.
If DOpus cannot show the "Duration" if you set the folder format to Movies, then, as you would expect, it doesn't seem to be able to calculate the total playing time for the files in the folder.
What you're seeing could be explained by Flat View being turned on. (If Flat View is on, calculation of the duration for the status bar may only happen if some other thing, like an info-tip, forces the calculation. This is done to avoid causing thousands of files to be inspected, or having to have special Status Bar configs for Flat View that avoids the duration calculation.)
My default is Details view. I pick a folder and I see total times filled in. I switch to List view and I can still see total times. If i select some files, I get times for selected and total times (I have both in my config... "{smp3}/{tmp3} (Selected/Total)"). If I refresh the page while in List view, total times goes to 00:00 and I can't get it back unless I switch to Details view. Selecting files also remains 00:00
My guess is that the background thread which calculates the lengths of the files is getting stuck sometimes.
The calculation depends on video codecs, and some (versions of) some codecs can go wrong (or simply take a long time) on certain files. That could also explain why I don't see it on my machine (as I probably have different codecs).
This is just a guess, though. It could be something else that I haven't thought of, maybe tied to a configuration option somewhere. It does not seem to be List mode by itself, though. (There was an issue with List mode behaving this way but it's been fixed for quite a while now.)
I don't have video codecs installed because I use VLC Media Player which has built-in codecs, maybe that's the problem? However in other view modes it works fine, so it is strange.
@platanos
As an additional or optional or alternative method to display audio file durations in the status bar i've just(!) created a new DO10 button with cd C:\Programme\TagRename @async:C:\Programme\TagRename\TagRename.exe {sourcepath}
The software has a fine status bar which i wasnt able to reproduce with DO10 commands. DO10 status bar displays durations of some audio file formats (e.g. MP3) but not all (e.g. APE, FLAC, WMA, etc.). My media collection consists of all kinds of file formats (M4A, MP4, AAC, WMA, MP3, FLAC, APE, MPC, OGG, ..) that's why the DO10 status bar isnt of much use on my PC. So on your PC you may want to think of creating a button too (Tagnrename was just a suggestion because it's a well-known and popular music file tagger).
i havent tried your status bar code so i cant tell if it etc. i am happy with my button and my motto is "Dont touch a running system."
Every machine has video codecs installed. Windows comes with some, programs you install may add some, etc. even if you don't explicitly install any yourself.
(If there were no video codecs, Opus wouldn't be able to inspect the files at all.)