I use Yosemite 10.10.5 and the versions of 2.7 and above keep crashing using 2.6 is fine but I don't know how to merge multiple Flv files together, please help me out here. file of video:2021-11-18 04-10-38.mp4
Official, current Avidemux builds for macOS are not backward-compatible as they need to include libraries from Homebrew. To obtain a current (i.e. supported) Avidemux build hopefully capable of running on 10.10.x, you have to build it from source yourself on your Mac. I don't have better news, I'm sorry.
ok cool