I've been doing photography for years, since I was 6 - now being 31 - and all the legal stuff can be found on places like Amatuer Photographer's website, along with much debate on this matter (as many of us have had run-ins with illiterate oiks who think its illegal to get a camera out in public)
If you ever get challenged you can refer the individual to the Home Office. Any challenge by the Police, PCSOs or street wardens need to be complained about immediately to their superiours. People have been arrested in places over a camera, and others issued stop and search. I'd imagine video recording might get similar issues in time as our practice spreads.