Stable RHEL 8 has not been released yet. AFAIK Red Hat don't publish training for beta products. RHCE 8 should go live in June, meaning that RHEL 8 will also hit stable at that point. I would expect training videos to follow.
RH124 v8.0 Video Classroom is already live in RHLS. RH134VC should be live sometime next week, RH199VC in early June, and RH294VC mid-June.
Let me know if you have any other questions regarding the VC release schedule.