Back in 2002 Volition released the source code for FreeSpace 2 engine after getting bought by THQ and the FreeSpace license was left with Interplay, the source code project that jumped on it initially left MVE support out and just offered re-encoded movie files in ogg format for download. No idea how legal that was but no one evidently cared if it was illegal. Not that it's a good idea to take that risk if you can help it of course. They later somehow added MVE support back so you could just copy the movie files from your discs/digital copies, that hasn't made any lawyers start barking either.
I wonder does the FreeSpace 2 engine and Descent 3 engine share any parts of them, maybe some of the things FS2 SCP has made over the years could be used with D3 too.