I found these and thought they were really helpful in explaining some fundamental concepts in introductory chemistry:
1. Periodic Trends video
2. Multiple Proportions video
3. Electron configuration and orbital energy video
4. Rutherford Gold Foil Experiment/Nuclear Model of Atom video
All four of these topics were emphasized on my first exam.
1. Periodic Trends video
2. Multiple Proportions video
3. Electron configuration and orbital energy video
4. Rutherford Gold Foil Experiment/Nuclear Model of Atom video