Re: Seriously, I want out of the HTML5 trial. I want to FORCE Flash.
You may want to try a quick fix that I have come across on Chrome. Open the Development Tools (CTRL + SHIFT + J) Click the cog or sprocket icon that's on the lower right corner of the window/section. On the newly opened panel search Override User Agent. Check that and select Internet Explorer 8 or Opera or something that doesn't have support for HTML5.
I truly hate the HTML5 player on youtube. I don't like being forced to use the flash player, but the HTML5 player is just defective. :(