How can you possibly know what the actual visibility was at the time of landing. You can't base it on a video taken 5 minutes after the event!
If you know KTM you will know that this mist/fog is due to temp/dew point combined with heavy city pollution and zero wind . it clears gradually when temp rise , not on and off like other places. TFN for instance where the "fog" is in fact passing Cu clouds hanging on the slopes. and where changes in VIS are immediate and on and off.