Hey Paul,
Thanks for adding H.264 support! Don't know if you noticed, but if you click on the description of a feature on the html5test result, you get a popup that shows the status (stable, experimental, etc.), point value, and 'compare' which in turn goes to a page that shows which browsers support the feature. There are several items that are supported by Chrome (with stable status), but not enabled in our Dooble.
Here, I can reliably get a system hang going to
https://www.youtube.com . Tried capturing stdout and stderr using your example and went to youtube (which immediately hung the system), but after a <ctrl><alt><num-lock><num-lock>, stdout and stderr were both 0 bytes (<ctrl><alt><del> doesn't work when Dooble hangs).
I can provide a system dump from one of these hangs if you ever need one.
Regards,