Me and many viewers don't like the way, vimeo degrades videos with a width below 1280 to SD quality bitrate. For normal widescreen content that's fine, but not for our special portrait over/under layout. I experimented in the past with rotation, scale to bypass this, but either vimeo degraded the content or the iPad refuses to play it, becaue it was regarded too HiRes.
Today I found a new way by omitting black borders on the top and buttom and by rotating to the right. So, clips originating on 16:9 can now be uploaded as 1280 x 1040. Viewed with an orientation locked to landscape and held as portrait, this results in 1040 x 586 per eye and a 108px gap. And this layout fits both the vimeo and the iOS size restrictions.
I hope to soon reupload in the new format, but for GRilli3D fans there is still no alternative to view from "Download".