Hi Stein Jin,
Are you referring to this video
SAP River Flights Demo Application - Part 1 - YouTube?
not exactly sure of the source code availability, but can suggest a few similar resources
Do we have sap river e-Learning portal ? like SAPUI5?
Are you looking for a dedicated community for River related queries ?
If so, all the river related queries are mainly posted in Hana groups.
SAP HANA Developer CenterSAP HANA and In-Memory Computing
Please note that SAP River is different from SAP River RDE .
SAP River is a new development language and environment for developing a complete SAP HANA back end application.
SAP River RDE is a web based tool designed for developers, business experts and designers to build UI applications based on SAPUI5.