For your own game / use - each to their own - was thinking of a gro pro chesty for an upcoming friendly where they had stated the same. Some academies use a GoPro on the youth players and asses from there (so they are recording their own players parents that have aready siged up).
If anyone on the FOP is under 18 then you would need consent from parents / guardian for its use (even if you were to keep it for personal use, there is no definition of what" personal use" is ...... yes inc that!)
For submission as evidence - various laws have been interpreted (from other walks of life in the UK) that the video and or audio is insumissable unless you have the consent of every person that appears on it either in picture or sound (good luck if you want to declare this and pass round the declaration to be signed pre match - maybe do it whilst explaining the spray tin, sorry couldn't resist)
BUT ....
A transcript of said video IS submissable, and no authorisation needed as it is not their physical picture or voice that is being used, only a written trnascript of such.