I just downloaded the current version of ClipGrab and manually inspected the package contents. Indeed, the binary is an Intel-only “Mach-O 64-bit executable x86_64” file.
From what I gather, ClipGrab is an open-source GUI for the youtube-dl command-line program. Since youtube-dl exists for non-Intel architectures, maybe it won’t be too difficult to compile ClipGrab for Apple Silicon.
I see that ClipGrab’s support forum is down, but maybe someone at support@clipgrab.org can say if an official Apple Silicon version is planned.