View Source ExTDLib.Object.VideoChat (ExTDLib v0.0.4)

Describes a video chat.

Name	Type	Description
group_call_id	number	Group call identifier of an active video chat; 0 if none. Full information about the video chat can be received through the method getGroupCall.
has_participants	bool	True, if the video chat has participants.
default_participant_id	MessageSender	Default group call participant identifier to join the video chat; may be null.

More details on telegram's documentation.