Audio Stream over TCP/IP?

Could someone explain how do this work in the background ?

For example, I used a Videochat session with someone, audio and video were working well. Suddenly I heard a strange rumor during few seconds. All the Chat session was recorded with a Desktop recorder. Afterwards watching the recorded Video again, the conversation and pause was correct, but the strange noise was not in the stream.

For example if the tcp/ip or any traffic was recorded with a Networkmonitor. Could it be reconstructed through .pcap file finding the strange noise ?

Or how do such a hoax work ?

Thanks,
loadP