Why has Lightroom stopped being able to display older videos?

[MontoyaCat]

I run the most recent version of Lightroom Classic on my iMac (OS 10.15.3). Noticed that I can no longer view older flip videos I have stored in my library. How do I fix this? (Please tell me that I'll be able to somehow axcess the videos again! I'm just sick over suddenly losing all the footage of my daughter's childhood!)

Strange ! symbol has started appearing on old videos.