Depth of focus for video recording
Well, your calculations appear to be correct, but the only calculation that isn't exactly known is the pixel size of your camera sensor. Either your calculation of the camera's pixel size on the sensor (at least when filming 1080 video) is off, or their recorded circle of confusion of that sensor is off. Or both. Though I find it more likely that their stored CoC value for that sensor is based on what is "reasonable focus loss" not on the actual pixel size, and so they have a larger CoC value than what you consider to be reasonable, as your reasonable is that the CoC is no bigger than a pixel.

Either way, calculating the differences based on resolution shouldn't be an issue. In the spirit of better safe than sorry, use your own calculation of the pixel sizes (0.016mm with the DoF result ~1.31m) as a basis. If you're going to test for half the resolution of 1080 (being 540) then you'll double the pixel size calculation (0.032mm) resulting in ~4m DoF.

To calculate for 720x576 (which is 576 resolution, not 720 resolution. Careful with that) you'd do (1080/576)*0.013mm = 0.03 (new CoC for calculation resulting in 3.44m DoF).

I'm not sure how you got 146m as a result though. Perhaps you input the wrong circle of confusion value?