MainActor, a commercial product for video editing on a Linux platform, has been discontinued. This means that the source code could potentially be made open-source. A petition is circulating to encourage MainConcept to consider releasing at least some of their code.
A similar initiative was started by the Blender Foundation many years ago, and they successfully bought the source code for something like a hundred thousand euros, and then released it as open source.
MainActor has always been a well reviewed product, although the price tag was generally too much for many people. A source code release from MainConcept would come in the form of a partial code base, with their proprietary encoding technology removed. An effort would need to be made to replace those parts with something like libavcodec. If Blender is a good model, the process will be slow, but the potential for an active community is vast. Today Blender has one of the largest, most enthusiastic, and fastest growing user communities out there.