ProQuest provides many useful video tutorials as well as their own database specific LibGuides.
These video tutorial and powerpoints give a great introduction to the capabilities of the EBSCO databases.
In 2013, Hackney Library acquired 80,000 new academic eBooks. This guide explains all the unique features of eBrary, including a virtual bookshelf and dedicated apps.
The National Library of Medicine has a host of animated tutorials, pdf guides, and web tutorials on using MEDLINE/PubMed.
JSTOR has published a few, short videos on its various database features.