libavformat branch: crashes on vidvox sample videos

[pierrep]

While testing this addon, the default sample video worked fine, but when I tried these, I got crashes after around 5-20 seconds. Also, CPU usage went through the roof. I've attached a screenshot of the stack trace in debug mode if that's helpful. The videos I tested are here: http://vidvox.net/download/SamplePackOneHap1080p.zip