[rascul]

If Apple is distributing modified vlc binaries without releasing the source of the changes when requested, is that a potential legal problem?

[Cthulhu_]

As always, it depends; VLC "the iOS app" is not the same as VLC "the binary compiled from source". The article itself says they couldn't find any code changes, and the theories are that a certificate was updated.

I don't believe an iOS distribution specific certificate falls under the license you're referring to, but I'm no expert on these matters.

[feepk]

As a developer of the VLC-iOS app, I can confirm that the binary itself is completely unchanged. It is indeed the signature that was updated.