SVIDEO means Separate Video. In other words there is no audio, picture only. The picture and sound are separated from each other.You need a separate audio lead for the sound. Connect your Svideo lead to your laptop and the other end to your video recorder, or whatever you are using, then you must have another lead to connect the sound from the laptops "audio out" to the video recorders "audio in". They are usually phono leads. One for Mono and two for stereo.
I hope this helps.