Kanchirk, thanks for writing as it offers me the opportunity to clarify.
The premise, at least for the core product, first release, is that for each video there will be two accompanying windows: the Table of Contents and the Links.
The Table of Contents will appear all at once and offer the user navigation within the video based on topic
The Links will appear as the topic is mentioned. Clicking on a link will pause the video and do one of two (?) things: open a page in your browser, or open a new video player (probably in a tabbed interface) with a video that explains that topic.
I don't anticipate transcript at this point, though we are actively working on closed captioning. I'm not sure what "Sub-title" would do.
Your fourth item is not on the agenda for the initial release but is certainly of very high interest.