In the Library module I get exclamation point with message "lightroom encountered problems reading this video". However, when double click the file, it opens in Loop view and will play. So, what is significance of the error message?
"In the End, we will remember not the words of our enemies, but the silence of our friends." ~Martin Luther King, Jr.
It may be a bug - does it happen all the time to every video or only videos from the last import? When you encounter this message if you quit Lightroom and restart will you get the same message with the same video file? Are these iPhone videos?