Its taken over a month for me to finally find time to fix YouTube5, during which I have had time to fully remember why I hate the default player. But, as of now, it is fully working again! You can now watch Vevo videos and all YouTube videos without flash even installed. Most people have probably stopped using this plugin in the meantime, but hopefully many of you will reactivate it and continue using it.
For future reference, if you would like to receive notifications when YouTube5 is updated, follow me on Twitter @verticalforest.