We're sorry about the trouble with Lightroom Classic. Since when have you been seeing this issue? Are you able to play that video's on your Mac? Where are you importing those videos from? Have you checked if there is audio in the video file or not? We're here to help, just need some info.
I've just started working with Lightroom cc, so I faced the problem from the beginning. I open the videos with quick time, videos from a dji drone or videos taken with an iphone. When I try to import from an external device iphone or external drive it says what I already wrote cannot read the video so it doesn't import. When I make it from the mac hard disk it imports the file but without preview and with a "¡" saying Lr has problems to read the file. Some videos have audo some not!
Google translation of the error message: "Some import operations are not carried out. Lightroom can not read the video archive. The archive has an incompatible type of compression."
Upload a problem video to Dropbox, Google Drive, or similar and post the sharing link here. We can see if the video imports into other LR installations, and if not, what might be incompatible about the video.
I upload one of the video, in this case also with audio. to drive
it is not a heavy video and whenever I try to import from an external drive it cannot import and if I try form the internal hard disk it seems it is imported but cannot read the video and is marked with "!"
Interesting -- my LR 11.1 / Mac OS 11.6 imports that video without any errors. I wonder if it's a Mac OS 12 problem -- perhaps someone with Mac OS 12 can try importing it.
Also, are you on an M1 (Apple Silicon) Mac?
I just upgraded my MacOs version to work with the last version of LightrommCC .... sorry no idea if its is a M1 MAc, it was bought in Spain some years ago....
The link is not working to the mediaplugs installation is not working.
"if its is a M1 Mac, it was bought in Spain some years ago."
The M1 processor (Apple Silicon) was released late 2020, so if your Mac is older than that, you don't have an M1. LR has problems with importing video on M1 Macs.
Here's a correct link for checking for Mediacore plugins that could be interfering with LR: