Software for splitting or trimming MP4 video without transcoding I occasionally need to trim an MP4 video or split a clip out of the middle. Up to now I've been using a great app called MPEG Streamclip which has all the features I want:


super light weight, opens instantly
gui for scrubbing through videos
keyboard controls for frame-by-frame, keyframe-by-keyframe, in, out, and trim
batch list so I can set up multiple splits without waiting for each to save
saves clips from MP4s without transcoding


A lot of this functionality was also available in Apple's Quicktime 7 Pro, although not quite as streamlined.

Unfortunately the last update to MPEG Streamclip was in 2012, and each OS update breaks it further. In Mojave the Streamclip GUI is almost useless, and it's 32 bit so 10.15 will kill it entirely. Same for Quicktime 7.

I'm sure I'm not the only person who wants to trim and split video on a Mac. What are the options for lightweight editors to trim MP4s without transcoding?

Edit to explain how this is not a duplicate of Is there an easy way on a Mac to split an audio file at defined intervals?:
This question is about splitting a video file, not an audio file, at points decided by scrubbing through the video, not on a defined interval. That question currently has no accepted answer, and the answers that were proposed do not apply to this question.
Avidemux is a lightweight editor that can split videos without transcoding: 


Start Avidemux
Open a file e.g. by dropping it into the Avidemux window 
Choose where your video should start and then click on the (red) “A” button below.
Choose where your video should stop and then click on the “B” button below.
Select an output format (e.g. mp4). Note: there are two mp4 versions. If one does not work, just try the other.
Click on the save icon. Avidemux will propose a new file name based on the old one adding an “_edit” before the suffix. The trimming takes less than a second.