well, i managed to find a langthy report about this system from a group called Urban Eye:
http://www.urbaneye.net/results/results.htm http://www.urbaneye.net/results/ue_wp10.pdf
inside i found that the footages are recodred on tapes (?!?) in 3 seconds time laps format, and each tape is kept for 31 days, and recoreded over and over for 12 times.
but it sounds a bit outdates to still use video tapes, not to mention expensive and troublesum.
a modern system, probably would use digital cameras and digital storage based on either Hard drive arrays or computer Tapes (which save multiple copies at a time for backups) and also use high end data compression to save space. but i was unable to find something about this in regard to london system.
there is also consideration about something called Data Protection Act that deals about saving and transfering this footages to others:
http://www.ico.gov.uk/eventual.aspx?id=5739
hope someone will able to digg out more info about this.
