Actually Canon 1DC can record at least 2 min of uninterrrupted video on Lexar 1000x - I've tried.
It created 2 .mov files and warned about it at the end.
Here is a small 12 sec video shot inside the store in 4K mode:
http://tests.dmitry.com/1DC/
4096x2160@24P, ISO 400, 1/30 sec, f/5.6, 35mm prime lens, manual focus on a fishing bowl's reflection