[Chullish]

Keep the Flashblocker extension enabled it'll prevent the "missing plugins warning" with the added benefit of giving a visual indication that a webpage uses flash incase you'd like to switch to a different browser. With the plugin.default_plugin_disabled set to false I'd miss out on embedded youtube videos (I can't find a youtube html5 converter for firefox)

[DLWormwood]

One of the key points about Gruber’s article is that he actually wants the situation you are trying to avoid. Basically, he wants to see how many of his websites will present HTML5 based content if the website detects a missing Flash install. ClickToFlash (not sure about Flashblocker) pretends to be Flash, as far as most browser detection scripting is concerned. Otherwise, it wouldn't know there is Flash to be defered in the first place.

[sid0]

(I can't find a youtube html5 converter for firefox)

Firefox doesn't support H.264. If you're using Firefox 4 you can opt in to the HTML5 beta and get a fair number of videos served as WebM, though.