I just tried d/l vids on Day 4. Fooey, I meant to sign up for this series and forgot!
Anyway, it looks like each day has individual speakers' vids separate on the page. When I've seen this in the past, I've learned to ignore the VDH results when clicking in the extension bar. Instead:
1) start the video for that speaker by clicking on it.
2) right-click on each video and let the "Video DownloadHelper" expand. Doing this on the first video shows the 3 separate resolutions. I chose the 1900x1080 and started to d/l.
3) I paused the video.
Do this for each subsequent video. As you move down the list, it gets more confusing since for each video, it ALSO shows the entries for the previous videos. The only way I know to tell them apart is that having chosen the first video's 1900 resolution to D/L, when I see the entry for the 2nd video, it shows the 3 resolutions for the 2nd video but only two resolutions for the first video (because VDH is downloading the 1900 resolution for that first video). So I then click on the 1900 resolution for the 2nd video.
Moving on to the 3rd video, I do the same procedure -- and it shows 3 video entries but only one having the 1900 resolution because the first two are downloading.
Continue this for all the videos.
It may be prudent to limit the number of simultaneous VDH downloads by altering the VDH options.
This technique has worked for me on other sites, and as a general rule, when VDH seems confused, right-clicking on the video sometimes gives better results.
Some sites disable right-click in an effort to stop user behavior they don't want. In Chrome, there's an extension called 'Enable rght click" which fixes those nasty sites. (Who are they to tell me what buttons I can use???) I assume there's something similar for FF.
I'm using Chrome (latest) on 'doze 10. (I used to be a FF user for YEARS, but Mozilla screwed me TWICE by changing the extension API TWICE so that authors had to rewrite their extensions. Some of my most favorite and useful extensions were never rewritten, and I blame FF for their short-sightedness in screwing the community. Never again!
(Not that I love Google; BTW, they're trying to reduce user privacy yet again by "fixing" user tracking for ads. Gee, wonder why...? IRL would you tolerate some little sneak following you around and every once in a while saying, "pssst, wanna buy a watch?") <sigh>).