Is it possible for video element to have no src attribute.
Yes it's possible.
The library you do use probably sets the srcObject property of your videoElement.
This property allows to set the source of your video directly to a MediaStream, a MediaSource, a Blob or a File Object.
Note that FF only supports MediaStreams currently.
Example for FF (inspect the element afterward)
navigator.mediaDevices.getUserMedia({video:true}).then(s=>(vid.srcObject = s));
<video id="vid" controls></video>
And a fiddle for chrome since it requires https protocol for GUM to work.
If possible, how to get src for that video
Well, there is not really an src so I'd say not possible.
You can still call yourVideoElement.srcObject, but this will return the object to what it was set (usually a MediaStream).
If you need to record it, you can then use a MediaRecorder.
srcorsource?document.getElementById('EKA-e2RERLzhCFy8AAEd').src