This page is just a reference of all the known Steam APIs, I do not know how they work. Please do not email me with questions.
UNDOCUMENTEDGetBroadcasterInfo
https://api.steampowered.com/IDOTA2StreamSystem_247040/GetBroadcasterInfo/v1/
UNDOCUMENTEDListOfUsersSpectating
https://api.steampowered.com/IDOTA2StreamSystem_247040/ListOfUsersSpectating/v1/