Thanks Deb. That was details explaination. Appreciated the help.It’s an Intermediate imo - with the proviso below*
I see a bill too short/stout and a bird too stocky for GW, the retracted neck does not seem to have a sharp enough angle or deep enough drop on the ‘u’ bend either imo - thus, the neck looks thick/stocky rather than the long thin retracted shape of a GW. Size is very difficult to judge in the field when in isolation so not really very helpful, esp in a photo and some GW females can seem on the small side (also see proviso below) The head looks fairly rounded to me not the triangular shaped head and long sloping forehead of a GW. Gape line is pretty hard to use as a criteria, shadow/fluffed up plumage/viewing angle can really distort the length as JA notes above. I have always struggled with this feature as a criteria in eg Tawny v Steppe Eagle!
Re. the video - the flight looks too shallow and fast to me to be a GW (which have a deeper and more relaxed flight more like a Grey Heron)
*The proviso is that GW modesta are supposed to be smaller than GW alba