If you look at the video, very closely, Seekeerz, you'll see that the second person in from the left at the start of the video is a woman who is holding an extending dog lead, with her soggy canine pal on the end of it. So I assume that it's her dog.
Yes I saw the lead but wasn’t sure who was actually holding it - as you say, the lads were probably just there at the time - not a lightweight dog, either.