I've been gradually making small improvements to a new version of VidSync that works with both Intel and the new Apple M1 processors, and with the latest versions of MacOS (Big Sur and Monterey).
The only feature missing from the new version is "portraits," the ability to save screenshots of particular subjects (like the markings of a fish) within a VidSync file, e.g. for keeping better track of individual animals if they go off-screen and come back. I don't know of anybody actively using that feature right now. I plan to add it back in to the new version, but Apple completely removed the under-the-hood technology I was using to create it, so I'll have to rebuild it from scratch with all new code. I'm not sure when I'll have time to do that.
There are still a handful of minor bugs to be worked out, but most users won't encounter them, and none of them affect measurement accuracy or make the program unusable. I've used the new version extensively myself and have sent it by email to about half a dozen people who requested it, and nobody has reported back with any major bugs. So it's not as polished as the old version, but at least it works with newer Macs.
Head on over to the Downloads page to get the new version if you need it.