I uploaded two videos with examples of using the tMongoDBInput and tMongoDBRow components that are shipping with JaspersoftETL 5.2.2 (Plus edition) and Talend 5.2.2+
I recommend you change the quality to 720p to watch the videos in better quality. I hope you find them useful!
Part 1: Using tMongoDBInput (and using Talend's built in aggregation engine):
Part 2: Using tMongoDBRow (and the aggregation framework):