Laws may vary from country to country, and these coming quotes are regarding photography rather than video, but this is from an American lawyer:
Members of the public have a very limited scope of privacy rights when they are in public places. Basically, anyone can be photographed without their consent except when they have secluded themselves in places where they have a reasonable expectation of privacy such as dressing rooms, restrooms, medical facilities, and inside their homes.
e.g., none of those apply here unless there is a camera in change rooms.
And from someone else:
However, in some situations you're not protected and can be held liable for damages. These, as you can see, are fairly obvious, common-sense situations and can easily be avoided:
Photographing on private property. You may not enter or photograph on private property without the owner’s permission.
Libel or slander. You can’t misrepresent facts through the use of a photograph or accompanying text.
Use of the photograph in a commercial application. You need permission to photograph someone for an advertisement.
Assuming some legal similarities, I'd say the cameras are there with the owner's permission, that libel/slander doesn't come into play, and it's not a commercial application.
The issue would be if there is not permission between the stadium operators and BSA? (Assuming they are not the same in this case.) Otherwise, cameras in the open spaces (canteen, courts, etc) may well be useful in handling disputes (fight in a game, etc), theft or similar.