@Suiseiseki >> You're confusing commercial and proprietary.

If I can:

1) Download the source.
2) Compile my own version.
3) Study it and make changes to it as I see fit.
4) Distribute such changes to 3rd parties at my discretion.
5) Freely share or sell the data I produce with it.

In my book it fully qualifies as free software.

Now, kdenlive and ffmpeg are built upon several parts that have other licenses than GPL. I can accept that compromise for complex pieces of end user software that have dependencies on other projects.

As long as these licenses do not restrict any of the above 4 points I'm happy, I will never accept any limitations to the 4 points above.

If we're talking about basic pieces of infrastructure such as the kernel or low level libraries I would prefer them being 100% GPL.