In light of the recent demise of MacTubes and YouView, I set off on the task of getting a solid fluid YouTube experience on my PowerBook G4. My system is a 1.67 GHz model with 1.25 GB of RAM and an SSD. Sadly, under HTML5, the PowerBook struggled to play YouTube under both Leopard WebKit and TenFourFox. Adobe Flash is such a insecure pig that I refuse to use it on my system, however the performance was marginally better. The tool I found was ClickToFlash 3.1.6 by Marc Hoyois. You can download this extension directly from Apple by going to "Safari" --> Safari Extensions Gallery. Once installed, the preference panel should immediately open, but if not you can access it by going to "Safari" --> Preferences --> Extensions --> ClickToFlash. @Dronecatcher also pointed out that Marc Hoyois also has an extension called ClickToPlugin. It's functionality is very similar but includes a few more features. You can download it off his site from here. I am adding it to the guide below but note that only a few settings are different. Hats off to @Dronecatcher for pointing this other tool out! These settings work great for me and I strongly urge any Leopard WebKit user to give them a shot for both speed and security reasons. "GENERAL" Placeholder opacity: 50% (Default) ✓ Show Flash source as tooltip __Allow invisible Flash/Plugins (CTP) (this will kill all background Flash/plugin processes on a site for security reasons) __Block Flash/plugins manually sIFR text policy: "Show Text Only" Flash to HTML5 conversion scripts: Use Defaults __Load Flash/plug in if HTML5 conversion fails (due to the insecurity of Flash, we never want it to load regardless) ✓ Use HTML5 media fallbacks (If QuickTime cannot be used, it will use the rather secure HTML5 instead) __Use a download manager "PLUG-INS (CTP ONLY)" __Quartz Composer Plug-in (Enabling can use a lot of CPU in drawing Quartz compositions) ✓ QuickTime Plug-In 7.7 (QuickTime can certainly load by default for streaming reasons) ✓ QuickTime Plug-in 7.7 (Not sure of the difference from the other plugin) __Shockwave Flash __Switchable Java Plug-in for WebKit __ Verified Download Plugin "CONTROL LISTS" Leave this tab completely at the default settings unless you have a specific reason to use Adobe Flash on a site. The final version of Flash for PowerPC is 10.1 and is notorious for security issues. "MEDIA PLAYER" Default Media Player: QuickTime Player __Load media player automatically (Leave unchecked to preserve CPU while site is loading) ✓ Show Preview Image (Loads preview from YouTube search page) Default Resolution: 360p (Higher End G5s and ridiculously built G4s maybe able to handle 720p ) Nonnative formats policy: Use only as a last resort Initial Behavior: Autoplay ✓ Instant Autoplay ✓ Include Media Sources ✓ Include Flash (this will make all Flash attempt to be played by QuickTime or HTML5 as a fallback) ✓ Include plug-in (CTP ONLY, forces all plugins to try and use QuickTime or HTML5 as a fallback) __Include the video's webpage __Include QuickTime Player __Include AirPlay __Hide "Rewind" button Sound Volume: 100% (Adjusting this may affect audio quality) "SHORTCUT MENU" __Always Allow __Always Hide __Load All Flash (Disabled for Security Reasons) __Load Invisible Flash (Disabled for Security Reasons) __View on Site (Would allow you to watch video in site rather than in QuickTime) ✓ Download Video (Allows you to save copies of videos) ✓ Open in QuickTime Player (Allows site to open in QuickTime if not done automatically) __Send via AirPlay ✓ ClickToFlash Preferences __Enable/Disable ClickToFlash/ClickToPlugin "KEYBOARD SHORTCUTS" This tab is entirely up to user discretion on programming shortcuts. DISCLAIMER: These settings work great for me and are a vast improvement over any other extension or tool that I have tried. That being said, I cannot guarantee that these settings will work great for everyone and am not responsible for anything possibly caused by them.