The L primes are great, but for video the Zeiss are just better. L lenses tend to breathe really bad, and the focus ring is just so damn touchy, and larger apertures if you move it a fraction of an inch it throws everything out of focus. I only wish I had bought all ZE's in the first place, I have sentimental attachments to some of my L glass and can't bring myself to get rid of it. But i'll tell you this, I've been using the ZE 50mm f/1.4 over my 50L, and it's half the price but just as sharp and I love the way it renders color.
Zeiss glass is sharp, it's built like a brick, the focus ring is smooth as butter, throw is longer, and has hard stops at macro and infinity (3 foot mark is always 3 feet, but with canon if you spin past macro or infinity you lose your focus marks). The color rendition, micro contrast, and bokeh are all beautiful (and consistent). My color correction time was cut down substantially (75% less compared to Canon glass). They are without a doubt superior to L lenses for video. Not that you can't use L glass for video, but if you're shooting video primarily go ahead and get the Zeiss stuff.