To resolve this issue, please try this solution:
1. Open RealPlayer.
2. Click the RealPlayer logo in the upper left, then Preferences. The Preferences box opens.
3. In the Category pane, click DVD.
4. Under Advanced, change the Colorspace from YUV to RGB.
5. Click OK.
6. Close and restart RealPlayer.
Try playing the DVD again.
If the issue persists, please see also: Sound plays but video is blank, frozen, or distorted