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. :(