if you're annoyed by youtube breaking flashblock, and simply do not consider allowing autoplaying videos to be an acceptable option, one workaround is as follows:

1) temporarily put youtube in your flashblock white list
2) install an out of date version of flash
3) clear your cookies/cache/etc

that way, whenever you go to a video it will tell you that flash is out of date, which will block the autoplay.

hopefully, flashbock resolves this quickly...