For those of us who use LR Classic as the primary way to manage and edit our thousands of photos and videos, the following workflow seems to be the only way to get videos into Lightroom CC/mobile, since LR Classic refuses to sync videos to the cloud and LR CC.
Open LR CC
Select the Album, which already syncs photos from LR Classic, ready for video import
Navigate to the video files in the Finder to be imported into the Album
Review For Import
The video files will then appear in that Album in LR CC and then sync to the cloud to appear in the LR mobile app.
This causes problems in LR Classic.
The corresponding folder which points to the original source video file now shows a duplicate virtual copy of the video. This is because LR CC has synced the video back to LR Classic as a virtual copy only. This duplicate copy is also visible in the corresponding Collection.
DO NOT DELETE THE VIRTUAL COPY from the LR Classic source folder OR the Collection, since LR CC is not aware of the original files showing in LR Classic.
However, you can REMOVE the original video from the Collection (not from the disc!), leaving only the virtual copy visible, to maintain the correct sync back to LR CC.
Despite this clunky way of forcing videos to sync from LR Classic to LR CC, it does ensure that all metadata on the original video file is synced to LR Classic.
All this would be unnecessary if LR Classic simply synced videos to LR CC along with the photos. Interesting to know if this is a technical difficulty (unlikely), or Adobe marketing philosophy…