I have looked for means to stop Brightcove videos from autostarting in Firefox and have come to the conclusion it isn't possible without external programming via something like Grease Monkey. However, I'm not proficient in javascript let alone GM. So I thought I'd ask here first whether what I want to do is feasible, or whether it's a fool's errand.

What I want to accomplish is have a site specific script executed to replace a string value on the run in that site's code. Specifically, what I am looking for is something GM-style that would do this:

if site_domain = 'www.SiteWithAutoPlayVideos.com'
  then replace_all('<param name="autoStart"             value="true" />',
                   '<param name="autoStart"             value="false" />');

Having looked through Super User for anything GreaseMonkey that might relate, I see notices that the sandbox GM executes scripts in has to remain separate for security reasons. So, I suspect I might be in for disappointment. BUT if it is accomplishable and somebody here can confirm it, then I will do my best to struggle through the learning curve and get this noisome little problem put to rest.

Yes, I have tried Flash Block and FlashDisable in order to attack this issue with no avail.

Thanks in advance for your time.