We now have another option for Tiger, Leopard, and also Snow Leopard for YouTube.
Bugs: Video may glitch for the first 2-5 seconds per clip before smoothing out.
Fixed: Having to click the video thumbnail twice is resolved in both the Leopard and Tiger app.
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For the Leopard and Tiger versions right clicking on the "whitespace" of background will bring up a forward/back/reload dialog. Leopard version has the ability to change from 720p/360p/240p. Click the Gear icon on the video screen and select 240p if you have playback issues. For Tiger click the HD logo to enable 240p. 360p is the default setting for both versions.
I also built a similar version for Snow Leopard. One advantage to this version is it has the ability to run in full screen mode. Grab the TenFiveTube-SL.zip.
Tiger users grab TenFourTube.zip / Leopard users TenFiveTube.zip
NOTE: Leopard users will need QuickTime 7.7 for optimal performance.
Cheers.
EDIT: Added YewTube as another option for 10.5. May work on 10.4 also, but not tested.