We actually already have most controls you listed. There is a button and a check box. There is a tab container (in Containers palettes). There is a drop down menu (for now it's called Combobox). Search box is pretty simple to create by just using a label (Text) and an input field.
As for scroll bars - what did you have in mind? Same for video. We can easily add a new component inside the editor, the but question is, what is going to be generated when you view the prototype in a web browser? I think scroll bars need to be a part of some container. We can add a video component - what would you like to see in a web browser?
Annotations and comments is something we are planning to add as well as general update to all components. We want to make sure we cover all standard HTML tags.