AJA Video Systems have implemented this Quicktime format for Windows. It is a 10 bit per component, YCrCb 4:2:2 format in which samples for 5 pixels are packed into 4 4-byte little endian words. Rather than repeat the details here, I suggest looking at the original definition on the Quicktime web site.
Supposedly there are images described as "YUV10" that are formatted similarly to this aside from the bit ordering (the correspondent mentioned having to run ntoh on the pixel data to reformat from YUV10 to V210. Despite 20 years of C, I've not heard of ntoh but I suspect it performs big-endian to little-endian conversion).