Video > SSRC Parameters

a=ssrc:1993357196 msid:GUKF430Khp9jEQiPrdYe0LbTAALiNAK AIfl2753ad6b1-31a6-4fea-8070-269c6df6ff0e

This line is used to signal the association between the RTP concept of SSRC and the WebRTC concept of "media stream" / "media stream track" using SDP signaling [draft-ietf-mmusic-msid]. As you can see, the first number is the SSRC identifier that will be included in the SSRC field of the RTP packets. Following msid: we have the unique identifier included  in the semantic.