Bob, nice video ! Shows more features than the still photo.
Neil, After referring to plate 82 of my 1987 edition of "Shorebirds" I'd agree that the "capped" appearance and bright supercilium are good features for Sharp-tailed Sandpiper, but this bird does seem to have quite a long, decurved bill.
On the other hand, your commenters overseas HERE
http://www.birdforum.net/showthread.php?t=211176 seem to be coming round to Curlew Sandpiper !