This one from the PDF (https://www.jcs.mil/Portals/36/Documents/Doctrine/Other_Pubs/ms_2525d.pdf) seems more recent symbology/nomenclature:Maybe it's based on altitude to determine if they are sea or air tracks. But then they would have to be flying low, so yeah don't know. It is strange they are showing up as surface tracks ie green cross
Did you find any info on what the classification of Neutral is . That would be interesting to see what they classify as being a Neutral target
all in all, I don't see anything inconsistant with them encountering drones along with the rest of the fleet which TheDrive reported on
Also, from what I can tell, the VisionMaster FT X band radar is a normal spinning radar that is also available commercially, it's not a 3D beamforming radar (like the AN/SPY-1 is for example), so it's entirely possible that it wouldn't be able to distinguish between actual sea surface and low altitude flying objects that are within the detection area. I haven't looked at the spec in depth.
Definitely the tracks on the video are yellow, compared with the SWAN ACE which is green, and the shapes seem to have more rounded corners, which would match with the newer table from the 2008 MIL-STD-2525D PDF.