@APonz , I too had this issue, along with some other people.
The solution is to set the graphics aperture to 1GB or less. If it is set to 2GB, it will produce this video issue and the NUC will not boot.
One option is to use Recovery Mode (hold down the NUC power button three seconds), enter the Intel Visual BIOS, and set the BIOS to defaults. The issue should disappear. The default aperture is lower.
You should really not adjust the video settings (aperture, etc.) in the BIOS. They are only used while the BIOS is active and, since Visual BIOS uses a fixed resolution (regardless of the capabilities of the monitor(s) present), they shouldn't need adjustment. Once you are in an O/S environment, the Intel HD Graphics drivers completely ignore these settings and dynamically adjust the amount of DRAM dedicated (etc.) based upon current demands. In fact, in the latest NUC models, these parameters are being removed from the BIOS since they have no bearing on runtime environments.
Interesting, seeing as these are the latest NUC models (NUC8 being the Coffee Lake/Bean Canyon models) and the setting is present.
Whether or not the settings need to be adjusted or not (I'm going to be the person that says maybe "should really not need to" might be the correct phrase, not "should really not", seeing as these settings are available in the 0056 BIOS as of 11/28/2018), setting the aperture to 2GB still shouldn't cause video corruption and freezing during POST as it does with the latest 0056 BIOS. This corruption was not an issue with the previous BIOS.
Yes, they are still present in these particular BIOS. I will presume that fixing real bugs is always going to be a higher priority than protecting folks from doing something stupid.
Since this issue wasn’t an issue in the last BIOS revision, I think one can safely assume it’s a new bug, no matter what you personally think should or shouldn’t be tweaked.