For having used some NLE software from the past, afaik, there is nothing with GUI for editing video on MorphOS.

Still, nothing is impossible if you're brave enough. You can perfectly use ffmpeg in command line mode and do NLE with it.

Cumbersome? Yes. Can do the job? Yes.

Edit for a more targeted answer at Amiga legacy:
All NLE software on Amiga was tied to the presence of a Zorro card. MovieShop was used with the VlabMotion for example, Broadcaster Elite with its eponymous hardware. And the most famous of the most famous was the Video Toaster from NewTek which were only available in NTSC standard. Nothing of all this gonna work with MorphOS unless maybe if you're using an Amiga4000 + CSPPC.



[ Edited by Tcheko 16.10.2022 - 08:07 ]