I have tried 3 different cables for TV-Out and finally found one that gives great audio and video quality.
Here is the cable:
Amazon.com: RND Power Solutions Extra Long 3.5mm to RCA Adapter Stereo TV-Out Cable for: Samsung (Captivate i897 and Vibrant T959), Nokia (N8, N86, X6) Smart phones: Electronics
Cable has high quality tips and was built for the captivate and vibrant phones.
Other Cables I tried:
* Standard AV Camcorder cable (switch red and yellow tips) low quality
* White AV Cable even worse
* Samsung OEM Cable - OK Quality