iOS feature request

- adding a button to exit a video. Currently, the only way to exit a video is by pressing the back button located in the upper left hand corner of a video. This causes to replay the previous videos (if I have been watching a series of videos in a row). The current back button takes multiple clicks to get through all of the previous viedeos I have watched in order to get back to the main menu where I can select a different topic.
- improving the playback video quality of videos within the app. If the same videos are played on YouTube, the graphics and animations of the videos are better compared to those played through the Khan Academy app.
- adding a favorite button to favorite a certain topic, category, etc as the app loses track of where I was when I last opened it/used it and resets to the main menu where I have to navigate to where I want to go from the beginning every time.