I've not yet received a good answer on this. From what I can figure out when exporting to HTML5, regardless of the export package, app, exe, scorm, playing of on-slide video cannot be controlled with a video playbar. The only thing we've been able to do it make it multi-slide video and span only 1 slide. The video's playtime is in sync with the slide's timeline.
Where flash video has a skin with a playbar, HTML5 relies on the browser to control the video. Our "browser" is whatever is playing the slideshow, so until that get's an HTML5 video player we won't have a controller for in-slide video.