I just wanted to thank you and append extra information for problems your solution also fixes.
I don't have a problem anymore and just came to add more information.
I have a netbook that I gave to my wife as a gift.
The problem was the netflix video and audio falling out of sync in all browsers. Horrible annoying, unwatchable annoying.
I am still having minor tearing in Netflix (minor, not going to put any more effort in).
Okay what is the base problem? Hardware. The lenovo S10-3 netbook is barely powerful enough to handle netflix with it's atom processor and anemic video hardware running Windows 7 Starter that no one likes-- no one.
So in order:
I tried running netflix in the Google Chrome browser. -- Better playback, same problems after a slightly longer span of time.
I bumped up the memory to the fastest 2GB module it would take which is the maximum quantity as well since there is only one slot. --No noticable improvement.
I removed as many (TSR) crapware lenovo helper utilities I could; veriface, something else (at this time I kept the hard drive drop protection utility because we are butterfingered people). But TSRs were heavily reduced. --Slight improvement, barely noticeable.
I defragged the factory installed platter hard drive which is very active, often. --No noticeable improvement.
I replaced the factory installed WD Blue 250GB platter HD with an Intel 330 series 180GB HD and cloned the old hard drive to it using Clonezilla. (Clonezilla no longer automatically lets you clone a bigger hard drive to a smaller hard drive even if the data will fit, you may need to resize your partitions and you will need the advanced menu options and specifically the -icds option http://sourceforge.net/projects/clonezilla/forums/forum/663168/topic/5125793
) -- Much better playback, same problem after yet more time and especially if ANY multitasking whatsoever. Resizing the window would throw it out of sync.
Remove the last TSR I felt safe getting rid of, namely the disk protection utility that tries to eliminate damage to your platter disk in the event of a drop. Didn't need this anymore, the new disk has no moving parts. --No noticeable improvement.
Turned off scheduled disk defragmentation. Reran the Windows Experience Index (in computer properties). --No noticeable improvement.
Lowered most of my video settings to turn off advanced features my non-gaming wife will never use. --Barely, any improvement.
Left hardware acceleration on. --No change in setting, no change in performance.
And here was the breakthrough.
In the post I am replying to, the avsforum member suggested setting the buffer doodad to 1500 in the Silverlight diagnostics menu.
I did not have a 1500 and was set at 1750.
The onboard video seemingly powered by gerbils on a wheel had a 1050 buffering setting which was the highest that was below 1500.
I used IE 8 in the regular standard windowed mode holding shift + alt then clicking on the playing selection to get the diagnostics menu.
This key combination also worked in Chrome when I tried it because I was curious.
--You sir are a man among men. This solved all of the audio and video syncing issues I had allowing a full episode to be played with the sounds matching the moving pretty picture. Thank you so much.