About flash videos, the flash plugin is based on swfdec (like on linux if you know it). Which means it's compatible up to flash 8 and quite slow in general. It's still ok to watch a couple vids on some sites, but for something like youtube, a much better way is to use HTML5 mode, or use a small userscript that converts Flash to HTML5 on the fly for the youtube links not available in HTML5 mode yet.
