Quoting the GPLv2:
7. If, as a consequence of a court judgment or allegation of patent infringement or for any other reason (not limited to patent issues), conditions are imposed on you (whether by court order, agreement or otherwise) that contradict the conditions of this License, they do not excuse you from the conditions of this License. If you cannot distribute so as to satisfy simultaneously your obligations under this License and any other pertinent obligations, then as a consequence you may not distribute the Program at all. For example, if a patent license would not permit royalty-free redistribution of the Program by all those who receive copies directly or indirectly through you, then the only way you could satisfy both it and this License would be to refrain entirely from distribution of the Program.
What this basically means in the words of every legal advice I've gotten over the years is that by distributing software that is under GPLv2 you run the risk of having to stop distributing it. While this is fine in an academic setting, if you actually build a product using this software, you are toast.
This section of the GPL is actually the major reason why many companies will go to great lengths to avoid using GPLv2 software in their products. Many people think it's the requirement to release the full source code — it's not. Releasing sources is rarely a problem.
Please, if you reply to this, don't fight straw men: software authors can choose any license they please and it is their decision to make. I'm not criticizing that choice. I'm just pointing out some consequences which might not be obvious to everyone, and which are particularly relevant in the case of heavily patented video standards.