It's almost of historical interest only, but everywhere except the Philippines and Malaysia, the last MPEG-2 video encoder/decoder patents have expired.
As *nixcraft noted, what it means is that there will never again be the risk of an MPEG-2 decoder being bombed in the libre operating system world.
The company that had the patents wrapped up for licensing, MPEG LA, told the world the last US patent expired on 13 February here .
The company's not turned over a new leaf or headed for the receivers since the patents expired: it's got a bunch of other license pool programs going, including one for the CRISPR gene-editing tool, and ATSC-3 TV standards.
Pooling programs like this simplify life for developers – the number of patents essential to MPEG-2 ran into hundreds, with dozens of companies involved (the complete list at MPEG LA is in this PDF).
MPEG LA's fees were trivial for electronics makers (for example, of DVD players) – originally US$2 per encoder, and the same per decoder, and as patents dropped out over time, it fell to tens of cents.
Yes, there is at least one free library that handled the standard, ffmpeg2. However, wandering around various forums, we note that the ancient standard is still attractive to developers working with a limited footprint, like Raspberry Pi, so there's still reason for people to try and develop new decoders. ®