First off, make sure you have the latest version of Quicktime installed. If not, you can fix a common issue by follow these steps:

1. Open up Quicktime

2. Go to Edit->Preferences->
Quicktime Preferences.

3. In the Quicktime Preferences
window, Go into the “Advanced” tab and UNCHECK the “Enable DirectDraw acceleration” box.

4. Click “Ok”

5. Enjoy my animations!