Hi spindritf -- I work for YouTube and have been looking into some mixed content issues with embeds. Mind if I email you and ask for some details about this scenario?
Barrym is probably right: HTTPS everywhere forces ssl for the site, but not for the embedded videos. Feel free to shoot me an e-mail though, no need to ask.
Hmm... Did I not embed these correctly? The project page as well as the embed links are plain http:// this is what it should be, no?
People using the HTTPS Everywhere extension will have the site URL as https, but not the embedded videos.
since the page is also available via https, using protocol relative urls for the embeds should fix the issue (src="//www.youtube.com/embed/SOpwHaQnRSY" instead of src="http://www.youtube.com/embed/SOpwHaQnRSY")
https://www.youtube.com/watch?v=SOpwHaQnRSY
https://www.youtube.com/watch?v=sA4Za3Hv6ng
The hyperlapse of the climbing video looks like an FPS game from a decade ago with texture refreshing as you get closer.