1) Forwarding hadeeths, it's hard to go into books and verify authentic hadeeths. What should we do if we want to propagate Islam? Should we forward it by just asking writing book reference?

2) Creating youtube channel and making short Islamic clips from the majalis of well known scholars, despite in this age we can't know when this scholar is going to change his faith ? Won't I be responsible for putting such a scholar majlis when he was good ?

In both examples you have a responsibility to ensure the authenticity of what they say and preach