Windows 7:Poor video quality
 

The new Windows 7 power plan settings affect more of your software than ever before. If you notice video playback quality seems poor, for instance, then

Click Start, type Power Options and click the Power Options link.
Click Change Plan Settings for your currently selected plan,
Click Change Advanced Settings, expand the Multimedia Settings section and make sure "Playing video" is set to "Optimise performance".

Alternatively, if you often play video on a laptop, then change the new setting to "Optimize performance" and you may see an improvement in battery life.