Our embedded QuickTime movies are not playing in Safari under Snow Leopard.
They play fine using Firefox on the same Mac, and play fine on PC's.
Movie sizes are usually around 200MB. Smaller (50MB) videos seem to work fine.
I've tried tons of different variations of embedded code, from straight <object>..<param>..<embed> tags to the QT_WriteOBJECT() javascript function in AC_QuickTime.js
When I watch the QuickTime cache folder, the temporary file stops downloading after about 1 or 2 MB. But, once it caches that little bit, you can usually hit refresh, and it will start playing.
We have 6MB DSL, I'm using Safari 4.0.3 (6531.9) and QuickTime 10.0 (51)
Here is a sample: http://www.thelifechurch.com/test.htm