I’ll have to try that method @Austin. Thanks.
Earlier today I started to make a quick tutorial on how I usually loop a clip.
I’ll share it too, as an alternative.
By the way, to create seamless loops, there is also this method explained by Aaron Nace in his tutorial on how to create Cinemagraphs in Photoshop. It can easily be adapted for Shotcut to create a looping GIF or a single-loop video that can be repeated in a project.
Not what @frew asked for. But it’s a nice technique to learn.