1. A method for generating a summary document of an online meeting, the method comprising: storing, in computer memory, at least a portion of screen data representing a previously presented portion of an ongoing online meeting; capturing a plurality of screenshots in response to trigger events, each screenshot i) being based at least in part on the stored screen data and ii) being representable as an image thumbnail, wherein capturing each screenshot of the screen data includes associating a timestamp with the screenshot, the timestamp indicating a point in time in the previously presented portion of the meeting; combining the plurality of screenshots, thereby dynamically generating a summary document summarizing the ongoing online meeting, wherein the image thumbnails representing the plurality of screenshots are for facilitating navigating through the summary document while the ongoing online meeting is still ongoing; and signaling for presenting, at a viewer computing device attending the meeting, simultaneously and while the ongoing online meeting is still ongoing, first screen data corresponding to a currently presented portion of the ongoing online meeting and second screen data corresponding to one of the plurality of screenshots in the summary document, wherein the second screen data includes stored screen data from a previously presented portion of the ongoing online meeting, and wherein the first screen data is presented picture-in-picture inside the second screen data or the second screen data is presented picture-in-picture inside the first screen data, wherein signaling for presenting the first screen data corresponding to the currently presented portion of the ongoing online meeting includes presenting live screen and audio data of the ongoing online meeting, and wherein signaling for presenting the second screen data corresponding to the screenshot includes displaying screen data from the previously presented portion of the online meeting corresponding to the point in time in the previously presented portion of the meeting indicated by the timestamp associated with the one of the plurality of screenshots in the summary document.