Videos do not open

Hello,

I am a new user of Lightroom CC and I am struggling with getting any video files created on my Sony A7iii to open/import in the current Lightroom CC. I've been scouring the web and have found some posts regarding an issue with dynamiclinkmediaserver.exe, but I am afraid I don't understand any of it or what to do. I don't even see this program on my computer.  All of the posts are geared towards MAC users. I am running Windows 10. I saw something else that suggested Lightroom doesn't support Sony codec XVAC S. But I tried importing a AVCHD video and that didn't work either. I really don't understand issues of codecs, etc. All of the files had a .MP4 extension. I also tried opening a .MOV file made on my iPhone. Nothing works. For all cases Lightroom CC says "This file does not contain a supported format." I should mention that all of these video files play fine in VLC or Windows Media Player. They are not corrupt. Any help geared towards someone who doesn't understand all of the technical stuff would be appreciated.

Thanks,

Paul