You know, when QT 32 died… we (my company) had to support it for close to 30 years, and Apple had neglected it for so long. The bugs were egregious and longstanding, and we’d developed our own alternatives for 90% of it. When they finally pulled the plug it was such a relief. QuickTIme was revolutionary but ultimately a spent force; it died sad and alone.
I just want to pour one out for Quicktime Pro 7, the most brilliant, most effective, most dead simple editing suite of all time. So naturally, that meant Apple had to go and fuck it all up with Quicktime X.
Maybe the best thing to do since you’re still running Mojave is to take these old divx videos and convert them to mp4 using HandBrake and then edit the new mp4. It’s not like you’re going to be losing a lot of clarity if it’s a shitty old divx vid, anyway.
Handbrake might do a lot of what you want. It’s free, and there are versions for Mac, Windows, and various Linux implementations.
I already had ffworks on my El Capitan machine. Never paid the shareware, so I must not have been impressed with it during the trial period. But I’ll reexamine it.
Obviously I’ve been mucking around with this question for a while before asking it here.