If you are shooting 36mp still images, you're going to be able to see a pretty significant difference when comparing cheap lenses to their pro level counterparts. Does the same hold true for video? Not really.
Why is video any different? Well unlike a still image, that you can stare at indefinitely and notice every detail, video is a bit more forgiving. Every 1/24th of a second another frame is flashing in front of your eyes. The amount of data/second that your video footage is played back at may end up effecting your sharpness more than your lens. You might have the sharpest lens in the world but your camera may record footage at a low bit rate or maybe your camera is super high end but once the footage was edited it was exported at a low bit rate.
Perhaps the biggest argument against ultra "sharp" cine lenses is that most footage these days is played back at 1080p (about 2 megapixels/frame). At 2 megapixels, it's hard to notice many details at all. Remember that no matter how cheap a 35mm lens is, it is made to produce a sharp image that is well over 20mp. Most of Canon's lenses are still working just fine on the new 50mp 5Dsr. In the video they did film at 5k but they still ended up showing the footage on a 1080p screen.
At the end of this video 3 people compare all of the footage and try to guess which lenses filmed which scenes. The professional cinematographer who had the best score was only able to guess 8 out of 18 scenes correctly.
Once again, it has been proven just how amazing and capable even the cheapest photo/video gear on the market today currently is. It also shows why a 50mm 1.8 lens is the absolute best deal for the money for any camera system. There is no reason not to own one.