Agreed. I feel the majority of the science behind this is simply keep things clean and minimal. I would hypothesise 'Get Email Updates' would do better than 'Get Free Email Updates', too.
I don't believe a statistic offers any significant social proof. Lots of faceless people i don't know have signed up. So what?
What was your plan had this flopped and you only had a few sales by the time you had to start shipping items? could you have brought down to a per-unit basis? did you have an exit strategy if it didn't seem worth your time?
However, the devices with the most users which don't have flash (read: iOS), can play h264, not WebM. That would make it likely to be more often h264 with flash fallback.
I don't believe a statistic offers any significant social proof. Lots of faceless people i don't know have signed up. So what?