Simple AppleScript to fix issue with Blackmagic Desktop Video devices not being detected in macOS Big Sur.
You can use this to create an Automator "Application" that runs this AppleScript when you double click on it.
Thanks to user "tdawg_07" for publishing the command-line to reload the BlackmagicIO.kext
https://forum.blackmagicdesign.com/viewtopic.php?f=4&t=121992