Using the AdBlock plugin, the latest Flash Player (11.4.402.265, who comes up with these?) and Youtube is not a healthy combination it seems.
On several computers I kept running into trouble with Flash failing altogether for most videos. Super annoying. After some experimenting and trying things I discovered that AdBlock actually breaks Flash. Likely because it removes the annoying video ads by disabling parts of flash. Meanwhile breaking the actual video playback, too.
I’ve figured out a way that works around this and seems to work fine. Using 2 additional plugins.
First, AdBlock should be configured to not remove ads from Youtube. AdBlock has a feature for this in the form of the little hand icon next to the address bar.
This will disable the ad filter for Youtube and riddle it with ads. But… Now go to the Safari Plugin manager and install the plugins:
YoutubeWide and ClicktoFlash
YoutubeWide has no settings but ClicktoFlash has a whole bunch. I use the defaults for the most part but changed a few to suit me, see marked images below.
This will remove any clutter, ads and rubbish from Youtube but also force videos to play in the widescreen format. So the actual video shows in a larger frame which is nice. On top of this, the ClicktoFlash plugin defaults to use HTML5 instead of Flash. But will use Flash if HTML5 is not available for that video. Also nice! I never had faster loading videos. Yay!